(at around 1h 50 mins) In the prison, as Silk Spectre and Night Owl are fighting the inmates down the cell block, Silk Spectre's boots go from high stiletto heels to flats.
(at around 1h 50 mins) When Nite Owl and Silk Spectre II first arrive at the prison riot, the first one to run at them is an inmate with long hair. Silk Spectre II kicks him to the ground. As they fight their way down towards the guard, the same man is seen again and he is then swept off his feet and clotheslined to the ground by Nite Owl.
(at around 1h 25 mins) The third and final inkblot shown to Rorschach by the psychiatrist is not the same after his flashback.
In several fighting scenes, Silk Spectre II's boots switch back and forth from flat boots to high heeled boots.
(at around 36 mins) When Silk Spectre I is getting undressed in her 1940's flashback, her black glove disappears when she clips open the neck of her dress.
(at around 38 mins) When the coffin is being lowered into the grave, Dr. Manhattan's glow is not reflected off of it. This is because Dr. Manhattan can turn off the glow if he so chooses. One would not be glowing at a funeral, so Dr. Manhattan in turn is not.
(at around 2h 10 mins) In this movie, the United States won the Vietnam War. However, one of Veidt's monitors is playing Rambo: First Blood Part II (1985), a movie about avenging America's losses in Vietnam. In Veidt's world, Rambo must be regarded as an imaginative science fiction movie set in an alternate universe.
(at around 56 mins) Dreiberg microwaves a carton of Chinese food with its metal handle still attached. While microwave instructions commonly prohibit customers from placing metal inside them for safety reasons the dangers of doing so are greatly exaggerated in the public mind. Small amounts of metal, like the handle from a Chinese food container, will likely not cause sparking and will generally, at most, cause damage to the microwave not a larger fire or an explosion.
(at around 10 mins) Some of the floating credits are reflected in Neil Armstrong's helmet. The back of the letters (or the reverse side) is what is facing the helmet. The reflection of the reverse side (or, the reverse of the reverse side) would show the text properly oriented. Therefore, both the credits and the reflection should appear as readable; the reflection should not appear backwards.
If you look closely at all the framed newspaper articles, especially in the opening credits, the articles themselves are just series of repeating texts and paragraphs. However, this may be intentional, as it is a convention in comic books/graphic novels for "minor text" to appear as scribbles or repeating text.
(at around 1h 35 mins) When Dreiberg is in his secret basement with Jupiter, showing her the night-vision goggles he wore as Nite Owl, he turns the lights off while she's wearing them, and approaches her. His pupils are not dilated, like they should be in the dark.
(at around 1h 27 mins) When Rorshach kicks in the door at the child murderer's house, the door bounces several times against the wall, showing a spring is holding it open so it won't swing back in the actor's face.
(at around 58 mins) When Dr. Manhattan is dressing, as he turns his head at the end, his CGI neck can be seen going through the collar of his shirt.
(at around 18 mins) When Dan meets Rorschach for the first time, his glasses are wet due to rain but not his face or hair.
(at around 12 mins) As the camera zooms out from the crime scene at The Comedian's apartment, the Chrysler Center is visible in the reflection of the glass, but is not visible as the camera zooms out far enough to be able to see where it should be.
Silhouette is shown kissing a nurse in Times Square in a variation on the famous photo from VJ Day celebrations. It would be odd for Silhouette, who in the comic is forced to leave the Minutemen because she is outed as a lesbian and subsequently murdered, would make such a public display of her sexuality.
(at around 18 mins) [director's & ultimate versions only] The Phil Caputo book, "Equation of Evil" seen in Hollis Mason's apartment next to the television during the Rorschach/Patterson-Gimlin Film (1967) news footage, was not published until 1996. Even in the alternate history, this book probably would not have just happened to exist 11 years early.
The opening titles show Adrian Veidt partying at Studio 54 with David Bowie in his Ziggy Stardust persona. Alternative time-line notwithstanding, Bowie had stopped performing as Ziggy by the mid 70s and was living and recording in Germany and Switzerland. (Bowie lived in New York City around 1980, by which time Studio 54 had closed).
It could be argued that this is a fan dressed as Ziggy, but, again, glam rock had become passe by the mid to late 70s.
It could be argued that this is a fan dressed as Ziggy, but, again, glam rock had become passe by the mid to late 70s.
(at around 9 mins) In the opening credits sequence the stem of the flower disappears and the flowers hover freely.
(at around 5 mins) During the opening fight, as the Comedian is thrown across the room, Director Zack Snyder can be seen huddling between the drawer and brick wall, lower, left-hand corner of the screen. (Snyder points this out during his "live" Blu-Ray commentary.)
At Karnak in some close ups of Nite Owl's face, the reflection in his goggles shows actor Billy Crudup in his motion capture suit covered in blue dots, instead of a full rendering of Dr. Manhattan.
In the Mars scenes, two moons of approximately the same size as ours can be seen in the sky. However, the larger moon, Phobos, is 1/4 the apparent size of our moon when viewed from Mars, the other moon, Deimos, is much smaller - 5% of our moon's apparent size. Neither moon is as spherical as depicted, nor clearly visible from the surface.
(at around 9 mins) In the opening scene there is a clip of Leonid Brezhnev and Fidel Castro reviewing a military parade across Red Square from atop Lenin's mausoleum. However the vehicle traffic is moving in the wrong direction. It should be proceeding southeast along the square (left to right) with the GUM department store in the background as a reference.
(at around 1h 6 mins) During the 1959 accident at the Intrinsic Field Laboratory, the door lock time mechanism uses a Nixie tube digit display. The '5' digit can be seen to be an upside-down '2'. This is a characteristic of Russian (or Soviet) Nixie-tube displays and therefore would not be used in a U.S. scientific facility.
Even allowing for the differences in the time line, it seems unlikely Blake's body would be released from an active murder investigation in time for him to be buried only 4 days later, much less have a finished grave stone in place at the cemetery by then. (This plot hole is copied from the book.)
Rorshach's mask works because of a gelatinous ink moving within a fine, almost plastic, fabric intended for Kitty Genovese. However, there is no reason why the patterns should be symmetrical.
(at around 15 mins) [director's & ultimate versions only] While Rorschach is exploring Blake's apartment, he hears the "ding" of an arriving elevator, which seems to produce two police officers. One says he "heard something", but if they were on a different floor, they wouldn't have heard Rorschach in the apartment.
(at around 1h 8 mins) Doctor Manhattan describes a "circulatory system" appearing on the grounds of a government base. However what is depicted is clearly the nervous system, as it features a brain and spinal cord, but no heart or lungs. (This error is repeated from the novel.)
(at around 21 mins) When Adrian/Ozymandias is being interviewed in his office the reporter states that he is the second Watchman to reveal his secret identity the first being Hollis Mason/Nite Owl Senior. Mason was a member of The Minute Men (the precursor to The Watchmen) which didn't form until he had retired and passed the Nite Owl mantle to Dan.
(at around 1h 23 mins) A newscast lists the arrested Walter Kovacs' age as 35, i.e born in 1950. However, the opening credits showed Kovacs as a child in the 1940s, indicating that his correct age is 45.
(at around 15 mins) Near the beginning of the movie, Hollis Mason (first Nite Owl) is listing his fellow Minutemen, but forgets to mention the Silhouette.
(at around 1h 20 mins) When Rorschach is tailing Dan and Laurie he VOs that they don't recognize him without his "mask." Rorschach otherwise consistently refers to the mask as his "face."