(at around 44 mins) When they are arriving at the church to save the first cardinal at 8:00 PM, the sun is much too high in the sky for that time of day, especially when contrasted with the lighting as they exit the church later.
When the Camerlengo has been branded, he assists with lifting a heavy grate, runs, and maneuvers the helicopter as if he has not sustained an injury.
At minute 40, when the physicist tears the page from the Galileo document, she clearly and carelessly folds it. Paper so old would be more fragile. However, one second later it's perfect again and she holds it with care even when she hands it in to Langdon in the car.
(at around 35 mins) When Langdon and Vittoria are in the archives, there is a shot where Langdon is looking at Galileo's document with Chartrand in the background behind the glass. In the next shot where the camera is on Vittoria, Chartrand is behind her, making it not possible for Chartrand to have gotten there in such a short amount of time.
(at around 9 mins) While Langdon is first seen swimming you can see by the dark stripes on the bottom of the pool that he's swimming sideways, but when Vincenzi is walking besides the pool, you can see this time Langdon is following the stripes, that means he's now swimming the length of the pool.
The blast from the antimatter bomb is described as about 5 kilotons. This is 1/3 of the Hiroshima blast. The thermal and radiation blast, even from several thousand feet, would have destroyed the Vatican and killed everyone below.
Retina scanners do not respond to dead eyeballs.
When the Cardinals are locked in the Sistine Chapel to vote for the new Pope, there is sunlight streaming into the room. In reality, sunlight is never allowed in the room and it is in fact kept in extremely low light as bright light would degrade the frescoes.
Parachutes are not part of the standard equipment in most helicopters. Further, experts tend to agree that it is almost impossible for the pilot of a helicopter to bail out without the helicopter going out of control.
(at around 1 min) In the beginning of the movie, we saw the Ring of the Fisherman of the dead pope inscribed with his name: "PIUS XVI". However, the inscription should be done in Latin style, which uses "V" instead of "U". Thus, the correct inscription should read "PIVS XVI". The Latin style of writing is evident in the Ring of the Fisherman worn by real-life Pope Benedict XVI, which is inscribed "BENEDICTVS XVI".
The equipment needed to store antimatter, and the quantity produced, is inconsistent with reality. Also, the Large Hadron Collider is not a particularly important instrument in antimatter research, and antimatter research is not an important part of the LHC's goals. However, it is established in dialogue immediately that the antimatter-production experiment is an unauthorized piece of research well outside of the LHC's actual mission, and that the few researchers "in on it" are creating an exceptional new method for producing large quantities of antimatter. While this is not realistic, it's deliberate and established in the movie's fictional world.
Throughout, Langdon is asking which way a statue points. Even as a Professor of Symbology, he would have to ask because the orientation of church buildings varied throughout the times. In early times, many church entrances faced East, while this changed during the Medieval Era and from that time, the apse was commonly placed towards East. So, Langdon was not able to know the direction of the statues for sure. Also, he has just got off an 8 hour flight and is in a strange city. It is likely that he is disoriented.
The kidnapper's accent changes throughout the film. When we first hear his voice on the video recording, he has an Italian accent and later on in the movie switches between American and Russian. However, this makes sense for a "chameleon" who is adept at disguises.
The search pattern that the Swiss Guard are using when they turn off the lights one section at a time is indeed not the most efficient; switching off half of the remaining lights at a time would be faster. However, it would also tip off the unknown kidnapper(s) - after the second time of the lights going on or off they'd probably disable the camera. By searching one-at-a-time, it is ensured that when the light in the camera room goes off, the Swiss Guard know exactly where the camera is.
(at around 28 mins) When Langdon and the rest first enter the Vatican Archives, you see the lights go off as they are shutting off power in an attempt to locate the bomb. But, as they go through the reading room, the screens on the computers are still on. However, lights and mains outlets are often wired on separate grids and it is probable that the Swiss guard were only cutting power to the lighting grids as their goal was simply to kill the lighting around the bomb.
(at around 1h 9 mins) When Langdon is trapped in the oxygen-depleted vault in the Vatican Archive, he tries to break a glass wall by shooting at it. The resultant impacts show the glass to be laminated safety glass. When the glass finally breaks under the weight of a cabinet it shatters into thousands of small pieces - showing that the glass is toughened safety glass.
(at around 1h 45 mins) When the characters are in the Necropolis, you can see their breath. The Necropolis is temperature/humidity controlled to protect the site. It is quite humid but not cold. You would not be able to see one's breath.
(at around 36 mins) When Langdon and Vittoria are reading the Latin excerpts, the Latin was in perfect punctuation. However, in ancient Rome, Latin was written without punctuation (i.e. no spaces, commas, periods) or capital letters.
(at around 44 mins) When Langdon and Vittoria are about to enter Santa Maria del Popolo, it's almost 8 PM. However, the shadows of the people in the piazza are almost directly under them, meaning the scene was filmed around mid-day. When they enter the second church one hour later, it's completely dark.
According to their origin, the members of the Swiss Guard speak Swiss German, which can be heard once briefly in their operations center. Nevertheless, not a single Swiss actor was cast for these roles but they were cast with German or American actors. Thus, the Swiss Guardsmen in the film speak German, Stellan Skarsgård, being Swedish, even with a heavy accent and wrong pronunciation.
The end of the movie has the priest jumping from the helicopter and pulling the parachute. The explosion takes place knocking everyone down and destroying several things with the down blast. It also throws benches around, rolling them great distances. The parachute would have been destroyed or at the least collapsed from the blast, but instead it stays in good condition and saves the priest.
In the end, the priest jumped out of the helicopter and it continued flying upward. This is not possible today, even with autopilot helicopters. They are designed to maintain a specific altitude and pitch/yaw to help stabilize the helicopter, but not to actually fly it like a plane has an autopilot.
When the bishop is being burned alive in the small church altar, the body is lowered by accident in to the fire and you hear the bishop screaming. Later you see a far away shot of the dead bishop hanging in the fire, but the body is not burning, not even the robe is on fire.
The lady scientist says the anti-matter device would explode and be equal to a 5 kiloton nuclear bomb. At the end of the movie, even if the helicopter was at maximum speed. It could not get high enough to protect the people or Vatican City. A 5 kiloton explosion above the city would create a fireball 120m and radiation burst of .97km. A thermal burst of 1.11km and a damage burst of 4.5km. A 5 kiloton bomb would have extended out to Rome even at the altitude shown on the altimeter before the explosion.
At the beginning of the movie, it is explained that the 9 days of mourn after the pope's death are called "Vacant Seat" (Sedes Vacans, in Latin). In fact, the period called "Vacant Seat" lasts until the election of the new Pope.
At minute 41, Langdon reads the secret text which is supposed to be in English. Although the actual Illuminati were formed about 200 years later (see other goof), and they were Bavarians (so the text would probably be in a Germanic language), the text is written in modern English, rather than the Shakespearean English that would make sense if it was written at that time.
(at around 2h 5 mins) When Langdon receives the Galileo-text from Cardinal Strauss, the cover illustration can be clearly seen. It shows an old man under a vine-entangled elm tree, the mark of the famous modern-day publishing company Elsevier, which was founded in 1880 and is dedicated to the publication of scientific texts. Though Elsevier takes its name and mark from the old publishing house of Elzevir, which, indeed, existed around the time Galileo lived (and possibly published texts by him), it is not the same company and the mark on the booklet used in the film is not the original mark of Elzevir from 1620, which would have been used on a Galileo-text from that time, but the modern adaptation used nowadays.
(at around 1h 40 mins) The car the assassin drives, a Volkswagen, makes a beeping sound when he remotely unlocks it. Volkswagens do not make this kind of sound.
(at around 24 mins) The camera begins a circular move around Father McKenna's office. As it passes between him and a window, the light dims on the back of his neck because the cameraman is now in the way.
(at around 44 mins) When the actors enter the church of Santa Maria del Popolo, they entered a different church across from the actual Santa Maria del Popolo.
At the end, when the new Pope steps out onto the balcony, he is centered on St. Peter's square, facing directly down Via della Conciliazione. In reality, this perspective would put him on top of the roof of St. Peter's basilica, not the window from where the Pope actually addresses the crowd. His perspective should actually be left of center, from his viewpoint, of St. Peter's Square. The view in the movie is about 30 degrees off from reality.
(at around 1h 40 mins) The Assassin was provided with a bail-out car, supposedly to be located on Via Giulia. The vehicle was actually parked on Borgo Sant'Angelo along the Passetto between the Vatican and Castel Sant'Angelo, which could also be seen.
(at around 3 mins) Early in the movie, the Globe of Science and Innovation at CERN and behind the Alps are seen. However. it is not realistic at all. It is mentioned that they are at ATLAS experimental area which is in Prevessin and it is impossible to see the globe from that place. If they are at the main site of CERN, then the Alps cannot be behind the globe.
(at around 9 mins) Early in the film, Langdon can be seen swimming in a pool purported on the graphic early in the scene as being at "Harvard University - Cambridge, Mass." The pool has Harvard athletic banners, but is neither the older pool in Cambridge (the "MAC") nor the newer pool, across the Charles in Boston (the Blodgett Pool). In addition, at 5:30am when he's swimming, both pools have an active collection of swimmers.
(at around 47 mins) Langdon and the Inspector General find the first murdered cardinal at just a minute or two past eight, the time the murder is supposed to have taken place. But the murderer has already escaped the basement, and the body shows obvious signs of death having taken place long before.
(at around 36 mins) In their first visit to the Vatican Archives, Robert and Vittoria are sitting the table across from one another. When Vittoria asks Robert "Do you need help with Latin?" the shadow of the boom mic is seen moving on Roberts face.
(at around 1h 5 mins) When Langdon is in the Vatican library, he passes the book he is reading over to Chartrand and asks him to look for any reference to fire. Chartrand glances at the book and mentions the word "seraphim". Directly above this is a far stronger reference to fire, "di fuoco", which actually is Italian for fire.
When the group finds the second murdered Cardinal (with the punctured lung), Vittoria attempts to give him mouth-to-mouth resuscitation after it's established that he's still alive and able to breathe. Anyone with any medical training (which Vittoria seems to have) would know not to attempt CPR on a breathing victim.
Langdon states that, after the death of the Pope and before his successor is chosen, the Camerlengo becomes Head of the Holy See. While the Camerlengo does, in fact, become acting head of state of Vatican City, leadership of the Church is taken up by the College of Cardinals.
(at around 18 mins) Vetra refers to antimatter as "an extremely combustible substance". The energy released in an antimatter explosion is based on particle annihilation, not combustion, and Vetra as a physicist should surely know this.
(at around 1h 50 mins) When the Camerlengo flew up in the helicopter with the bomb, Vetra was looking up at the sky like everyone else. As a physicist she should have known that looking directly into a 5 kiloton matter-antimatter explosion at that range would result in immediate and permanent blindness.