Revealing mistake: When the kids step out of the water and walk towards the house, the floor is already soaking wet from previous takes.
Continuity mistake: Liesl creeps through the window and explains herself to Maria, standing by the middle of the bed. When the angle changes she is by the side of the bed. Then the angle changes and she is back by the middle side.
Continuity mistake: Christopher Plummer throws down the drape the kids used for clothing on the ground. Then he walks away and there's a clear shot of the ground and the drape has vanished.
Continuity mistake: In the scene right before "Edelweiss", the Captain is asked by the children and Maria to play something on the guitar. The Captain is holding a glass in his right hand and then proceeds to raise his left hand in a negative gesture. The shot changes, and the glass is now in his left hand- with his right hand raised to gesture.
Continuity mistake: When Maria and the children are in a carriage riding around Salzburg, singing Do-Re-Mi, at one point (when she is sitting facing the kids) they pass a shop that is painted in a very distinct color and with a distinct sign (Frisor = a hairdresser) A few seconds later, as Maria turns around to sit forward in the carriage, they pass the same hairdresser.
Continuity mistake: During "Do-Re-Mi" Maria's hair is blowing in the wind in the long shots but is perfectly combed in the closeups.
Continuity mistake: Right after the boat tips over, the children change places between the first shot and the shot that shows them coming up out of the water. Most notably, Louisa moves from being over the left, in the front, to over the right and carrying Gretl out of the water. She doesn't have enough time to move back and pick up Gretl.
Revealing mistake: In the scene where Captain von Trapp takes a Nazi flag and tears it in two pieces you can see him searching for the correct place to tear. If you look closely you will see that a small incision has been made already so it tears more easily.
Continuity mistake: Nicholas Hammond (Friedrich) was not a natural blond. The first scene to be shot involving him was the "My Favourite Things" scene and you can see that his hair is pale auburn. After this scene was shot, the directors thought that he would look better if his hair were lighter, so they applied an early form of bleaching agent to his hair. In scenes which were shot after this (notably the children's first entrance to meet Maria which occurs before the "Favourite Things" scene) his hair is very, VERY blond, almost white. In fact, if you scrutinise his hair closely throughout the film, it is a different colour in practically every scene, depending on when the scene was shot and how much of the bleaching agent had been applied.
Revealing mistake: When Gretl runs up to Uncle Max saying, "Can we really keep the puppet show, Uncle Max?", you can see Marta in the background begin her cue too soon as she starts to run up to Uncle Max in the middle of Gretl's line, but quickly stops herself. Then after Gretl finishes her line, Marta carries on and runs up to Uncle Max with the rest of the children and says her line.
Factual error: The von Trapps are shown walking over the border to Switzerland after a short drive out of the centre of town...except Salzburg is about 200km east of Switzerland. If one walked across the border at Salzburg, you'd be entering Germany, which is where (I believe) the people they were trying to get away from lived. Take a look at a map.
Suggested correction: Even though the von Trapps were 200km from the Swiss border, in the last 5 mins, they received a car from the sisters at the convent and the sisters disabled the cars of their pursuers.
Captain Von Trapp was clear, when they were about to hide, that they would drive into the mountains in Salzburg (which the movie did a close up on to show it was those mountains specifically) and walk over them on foot confirming the movie is pretending those are mountains into Switzerland. The director himself admitted this when the real Maria Von Trapp complained of this error. He said "In Hollywood you can make up your own geography."
Audio problem: During the bedroom storm scene singing "My Favorite Things", Marta is sitting next to Fräulein Maria and she gets wrapped up in the moment of Maria singing and mouths "feel so bad" - she's not supposed to be singing.
Continuity mistake: When the children are singing for the Baroness, the Captain joins them and enters the room. In this wide shot, we see Liesl only begin to put down the guitar. In the close up shot of the children, however, the guitar is almost all the way down.
Continuity mistake: During the Folk Festival, near the end of Do-Re-Mi, while they are singing the "with jams" Gretel is in the front row with Kurt directly behind her, but when it zooms out, Kurt is further along and Gretel is between Louisa and Kurt. (00:02:30)
Continuity mistake: The Captain sits on the middle of the couch to sing Edelweiss, but appears sitting on the far left side a frame later.
Audio problem: During the song "The Lonely Goatherd," Maria sings, "Men drinking beer with the foam afloat," Marta blows foam from the cups into Maria's face, and she coughs. You can see that Julie Andrews' mouth is not at all in sync with the coughing on the recording.
Continuity mistake: Part way through the "Do-Re-Mi" sequence, when Maria and the children are walking down the steps overlooking Salzburg, the sun changes direction. At first it's behind them, so their faces are in the shade. Then suddenly the light is in front of them, and their shadows have changed direction too.
Factual error: At his wedding, Captain Von Trapp is wearing three medium-width rank rings on the cuffs of his uniform (similar to a Commander in the Royal Navy and US Navy). In the Austro-Hungarian Navy, in which he served, this rank badge did not exist. Von Trapp actually held the rank of Korvettenkapitän (Lieutenant-Commander), indicated by one medium ring and one narrow ring. Even had he held the rank of Linienschiffskapitän (Captain), he would have worn one medium and three narrow rings. The only rank which had vaguely similar insignia to that in the film was Linienschiffsleutnant (Lieutenant), with three narrow rings. Even allowing for artistic licence re Von Trapp's actual rank, the insignia he is wearing simply did not exist.
Continuity mistake: In the scene right before the song "Sixteen Going On Seventeen", sung by Liesl and Maria, Liesl looks down and says a line ending with "...and he stops loving you." and then looks up. The shot from behind shows her looking up again. (02:25:45)
Continuity mistake: Just before the Captain is about to sing Eidelweiss to the children, Max, Maria and the Baroness, the Baroness says to Max "Well why didn't you tell me, I could have brought along my harmonica." She has a glass of champagne in her hand and is about to take a sip but the camera cuts back to the Captain starting to sing and the glass is back resting in her hand. (01:21:30)
