In the opening scene, when the helicopter camera zooms in on Maria, it's bright and sunny, but when it switches to a regular camera, the sky is suddenly cloudy.
Just before the Captain sings "Something Good", he touches Maria's face with his right hand. In the next shot he lowers his left hand.
Captain Von Trapp's car demonstrates a dual personality - at least, the convertible top does. In some scenes (e.g. when the kids drive up to meet Von Trapp after his honeymoon with Maria), his exquisite convertible has a black top. In other scenes (e.g. when the family is caught by the Nazis in mid-escape while pushing the car away from their home), the car has a white top.
During the thunderstorm, when Gretl runs into Maria's room, she throws open the door and we hear and see it bang on the opposite wall. However in the next shot, a close up of Gretl we see it bang against the wall again in the background but no sound is heard.
At the wedding, Maria ascends the steps at the end of the aisle. Captain extends his hand to Maria and she accepts it on the top step. They are not holding hands as they approach the altar.
When Maria requests the family to "thank the Lord" when they are having their first meal together, she recites the Protestant grace and the Von Trapps pray in a Protestant manner with their hands folded and heads bowed. Being a Catholic family, they would have started and finished with a sign of the cross, and the Catholic grace, "Bless us O Lord and these thy gifts" etc.
At the wedding, Captain Von Trapp wears a uniform with 3 gold sleeve stripes and a circle. This is the insignia of a senior lieutenant in the Austro-Hungarian Navy. His sleeve should have had 1 wide stripe with 1, 2 or 3 narrow stripes plus the circle, depending on how senior a captain he was at his retirement.
The names and ages of the various Von Trapp children were invented for the film. Most of Captain Von Trapps children were adults at the time depicted in the movie. His eldest child was not a "sixteen going on seventeen" year old girl named Liesl, but rather Rupert, who was a practicing physician at the time of the Anschluss.
The Captain and Maria return to Salzburg early from their honeymoon when they hear about the annexation of Austria to Germany. They pull up to their home, and the Captain quickly tears up a Nazi flag that has been displayed there. It is clearly warm and there are leaves on the trees - late spring or summer. The annexation of Austria took place on 13 March 1938, and it would therefore have been colder, grayer, and there would not have been any leaves on the trees.
The Von Trapps have said that Georg was not the strict and humorless martinet depicted in the film. Although something of a disciplinarian, his children also remembered him as very warm and more similar to how the character ends up at the end of the film. One of Georg's children said that it was actually Maria, who had experienced a sheltered and emotionally stunted upbringing, who actually experienced an emotional "thawing" during the relationship.
Georg von Trapp was an officer in the Austro-Hungarian Imperial Navy in World War I, commanding ships based from ports on the Adriatic coast of Croatia, an Imperial province. In 1918, the Empire was dissolved, leaving Austria a landlocked country, and Von Trapp out of a job in the process. "Austrian Navy" sounds like an oxymoron to viewers unaware of the historical context.
The Mother Abbess tells Maria that Captain Von Trapp's wife died "several years ago". A distressing number of people have heard this as "seven years ago" and wonder how she can have given birth to the five-year-old Gretl.
Liesl tells Maria that she and her siblings do not know how to sing when it shows her and Rolfe singing "16 Going on 17" in a previous scene. However, Liesl is indicated as being a rebellious teen that doesn't want the rest of her family to know (her romance with Rolfe, for instance, isn't known to the rest of them), so there is every chance that she knew how to sing. Besides, being the oldest, she most likely remembers her mother singing.
Do Re Mi. The children learn the song while wearing their play clothes. They are later seen in other clothes then back to their play clothes. However, it is obvious from the various scenes that they are singing this song over the course of several days, hence the clothes changes. The children are shown in other clothes while in town or in the house grounds, while wearing the play clothes climbing trees or in the countryside - suggesting they wear them for activities where they may get dirty (so as not to spoil their good clothes). Additionally if it were the same day, it would be strange for Captain Von Trapp to drive all the way to Vienna to meet Elsa and Max and then drive back.
On their first day out, Maria asks the children what songs they know. Friedrich responds that they "don't know any songs". Later when the guitar is offered to Captain Von Trapp and he is deciding what to sing, Friedrich can be heard saying "sing us something we know". Given, however, that they haven't had much music for at least five years, it's likely some wouldn't remember how to sing, but would still know some songs as they listened to them. The fact that Friedrich asked for "something we know" is, in fact, proof of that.
When the Nazis are searching for the family on the roof of the abbey, one of the actors shines his flashlight accidentally toward the "mountains," and it throws a beam of light on the painted wall, revealing the fact that the Alpine scenery is painted, not real.
When Captain Von Trapp and Maria come back from their honeymoon, he pulls a Nazi flag down from above his front door. As he does so, he is obviously searching for the correct place to tear the flag and eventually finds a slit which has been marked by the prop people. You can also see the slit going down into the flag.
When Maria is singing "My Favorite Things" to the children the first time, during the first verse and chorus, one of the girls, Marta, is seen miming the words to herself - especially the last line of the chorus, "... so bad!"
Immediately after "Do-Re-Mi" as the children finish their stair run, we will see Kurt trip slightly on the stair. As the camera fades away, the actor can clearly be seen looking at a crew member (possibly the director) and grinning sheepishly as if recognizing his mistake.
When Maria first leaves the convent, one of the bars in the iron gate is visibly cut away to make room for the camera.
When the children welcome Maria and the Captain home from their honeymoon, the car is seen lurching as Max shuts it off indicating it is
still in gear.
When Maria sings in front of a church in Salzburg, there are zebra crossings behind her. Zebra crossings were adopted for the first time in 1951 in England.
During the opening credits (for Screenplay, Associate Producer and Director), the Hotel Europa Salzburg can be seen in the distance to the left of the Collegiate Church that is in the foreground. The Hotel Europa Salzburg was built in 1957 and is obviously more modern than the surrounding buildings.
The guitar played throughout the movie is a Goya guitar from the Levin Company of Sweden in the early 1950s.
When Maria sings "My Favorite Things" to the children during the thunderstorm, the Captain comes in to stop the fun. As she watches the children running into line, she says something like "Wha-" after bumping into the Captain, but her mouth doesn't move.
During most of the song "Edelweiss", Captain Von Trapp appears to strum the guitar appropriately. We hear the song end with a single chord running from the lowest string to the highest, yet he ends by plucking only the first (lowest) string with his thumb.
Before Maria teaches the children how to sing "Do Re Mi," she tunes the guitar. She turns the peg which tunes the high "E" string, but a lower pitch being tuned is heard against the high "E."
When Maria and the Captain meet the children after their honeymoon, when the children are telling Maria they are going to sing, Friedrich approaches her and he obviously tells her something but there is no sound of it.
After Maria's wedding there is a sequence of tolling bells. In the last shot of only one deep bell tolling, we can clearly hear the bell ring well ahead of the clapper actually striking the bell's rim on screen.
In the final scene of the film, the rippling of the grass shows that there is a helicopter hovering above.
When the Von Trapp family is trying to leave their home to escape from Austria, Maria and the girls are following the car as it's being pushed through the courtyard by Capt. Von Trapp, Max and Kurt. Friedrich is steering and he exits the car to open the gates of the estate. As he turns to go back to the car, you can see him step over one of the ropes being used to pull the car off screen as the men push it.
When Maria and the Captain are outside the gazebo, there's a stage light visible in a few shots.
The ending scene where the family is walking up and on top of a grassy hill is not Switzerland at all but in Germany itself, the Berchtesgaden, Obersalzburg to be exact, where Hitler's Bavarian hideaway was.
At the beginning of the film where Maria is dancing on the top of the mountain and she hears the bells of the convent ringing, firstly the mountain is so far away that there is no chance that she would hear it, even with bionic hearing. Secondly, she runs down the mountain to the cathedral in minutes when it's about 20 miles away.
When the children and Maria first meet, Friedrich places a frog in one of the pockets of her skirt. None of the children's uniforms had pockets, so there was no way for them to hold a frog without their father or Maria noticing.
Captain von Trapp could not have afforded such a large house on his naval pension. In reality the family lived in much more modest circumstances.
After meeting the children, Maria finds a frog in her right front pocket. However, when she is surrounded by the children, none of them are holding anything in their hands, and at no time do any of the children actually put (or appear to put) anything in her pocket.
When Maria eats her first meal with the Von Trapps, they all use their eating utensils the American way, i.e. with the fork in their right hand.
During "My Favorite Things", Brigitta is seen covering her head in fright a second BEFORE the lightning and thunder.
When Rolf gives the telegram from Berlin to Liesl, his black feldmutze still has the Austrian red-white-red roundel on it.
After the Von Trapp family have been stopped by the Nazis after pushing the car out of the gates of the house, and then allowed by Herr Zeller to take part in the music festival, when Maria and the Captain go to the front of the car, he gives her a "cross-fingers" sign. This is the sign for luck in many English-speaking countries (and maybe others too), but in German-speaking countries it is "Daumen drücken" ("press thumbs") for luck, not crossed fingers. If Christopher Plummer really had been Austrian, he would have pressed his thumb down on a vertical clenched fist.
During the final scene of "Do Re Mi," as the children are jumping up and down the steps, Louisa forgets part of the choreography. She glances at the other children, then tries to correct her placement by moving to another step.