Continuity mistake: In the confrontation scene between Peter Bailey and Old Man Potter, Peter moves from behind his desk about four feet away from Potter, to sitting on the edge of the desk about 18 inches away from Potter. Also the coat on the coat rack behind Potter changes from hanging from the collar loop to just the collar itself.
Continuity mistake: In a scene near the end of the movie, George enters the Building and Loan with a Christmas wreath on his arm. On hearing that he has a phone call from his brother Harry, he tosses the wreath on a table and picks up the phone. In the next second, the wreath is back on his arm.
Continuity mistake: In a scene early on in the film, where George Bailey (James Stewart), Bert (Ward Bond) and Ernie (Frank Faylen) chat in the street, they suddenly stop due to the appearance of Violet (Gloria Grahame) in her "this is what I wear when I don't care how I look" dress. The camera cuts back to them and we see a dark haired woman in a hat pass in front of Ernie's taxi. As Violet crosses the street and gets honked at, we see another shot of the boys staring after her - and the dark haired woman passes in front of the taxi again.
Continuity mistake: In the scene at the railway station where George and Uncle Billy are waiting for Harry, Billy reaches in the bag of peanuts and pulls one out. As the camera angle changes slightly, Billy's hand is suddenly back in the bag and pulls out another peanut. Also the man in the background wearing coveralls and a locomotive cap changes his position, and has lost the pamphlet he had just placed in his back pocket.
Continuity mistake: In the scene where Old Man Potter is offering George a job, nearly all of the items on Potter's desk - skull, lighter, eye glasses, small ink blotter and magnifying glass - change position as POV shots change from Potter to George. In some cases items disappear completely then reappear, ie. eyeglasses, ink pot and two pens, the liquor case and bells on the corner of the desk, and the pencils beside Potter go from none to one to two, and then none again.
Continuity mistake: During a confrontation between old man Potter and Peter Bailey at the Building and Loan, Potter's bodyguard stands behind the wheelchair on its left side. But in the close-up shot of Potter, the arms and hands of his bodyguard can be seen extending from the right side of the wheelchair. In the next full screen shot, the bodyguard is seen on the left side of the wheelchair once again.
Continuity mistake: When Ernie is about to take George during his "never born" sequence, if you look at the building next to the taxi, there is the Indian Club. As Ernie is driving along around 20-30 seconds pass inside the cab. When we see outside the cab and Ernie signals to the policeman, you can see the cab has only traveled roughly 20 meters from the Indian Club.