Continuity mistake: When George crashes his car into the tree, the front of the vehicle is against the tree, but the next shot of George exiting the car shows the vehicle off to the side of the tree.
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: When George Bailey crashes his car into the tree after leaving "Martini's Place", notice its position against the tree; an upward angle. In the ending scene when he's running home he cheers and taps the hood of the same car, now at a downward angle.
Continuity mistake: When George Bailey is going to jump off the bridge, watch the snow carefully. In one of the shots where Clarence is shouting in the water the snow all of a sudden quits, then it goes back to snowing when George jumps in.
Continuity mistake: When George is kicking stuff and knocking stuff over in his house (after yelling at his children), his hair is messed up. In the next shot, it's combed 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 Uncle Billy sees Potter in the bank, he walks to the teller window and there's no line, but a second later there's a line of a dozen or more people behind him.
Factual error: In the drugstore scene where Mary whispers in George's bad ear, there are several shots showing a Coca-Cola thermometer on the wall where George hangs his jacket. This particular scene was to have taken place in 1919, but this particular thermometer wasn't produced until 1939.
Continuity mistake: In the scene on the bridge, before Clarence jumps, George's hands do not indent the 2-3" of snow on the rail. In a later shot, after George jumps, you see two snow-less spots on the railing.
Factual error: In the closing scene Ernie the cab driver is wearing a military shirt with an Air Force insignia on the sleeve, but we were told earlier that Ernie parachuted into France. His shirt should have had a different patch.
Continuity mistake: When the pharmacist hits young George, the amount of blood coming from George's ear changes back and forth between long shots and close ups.
Continuity mistake: The old man's cigar disappears when he sends young George to deliver a prescription.
Continuity mistake: The bouncer in Nick's bar has his right hand grasping old man Gower's right shoulder, but the next shot when the bouncer throws Gower out of the bar, the bouncer's left hand is now holding Gower's right shoulder.
Other mistake: During Harry's party, when George is outside talking to his mother she encourages him to see Mary and George says "Point me in the right direction." He then exits right and immediately returns. As he passes by, there is a glitch in the film and for a brief moment everything speeds up. This is most evident if you watch the people dancing in the house because they appear as though they clicked into "fast-forward motion" briefly and then return to normal.
Factual error: Since it's cold and snowing throughout most of the movie, how come you never see the people's breath? This is because when they filmed these parts, it was very hot outside, but it's still a mistake.
Suggested correction: Seeing a person's breath is not entirely dependent on how cold it is, but rather how much or how little humidity there is in the air.
Seeing your breath is based on how cold it is, however, with high enough relative humidity, you're able to see your breath in warmer temperatures. If it's cold enough to snow, it's cold enough to see your breath, regardless of what the humidity is.
Continuity mistake: The pen in Potter's right hand is instantly placed on his desk as the scene cuts from him to George Bailey when Bailey is begging for Potter's help in replacing the missing $8,000.
Continuity mistake: Outside of Ma Bailey's Boarding House, Clarence is leaning on a mail box, holding his copy of Tom Sawyer. The position of the book changes in Clarence's hands as the shots quick cut from him to George Bailey and back.
Revealing mistake: Near the beginning of the film, young George already has blood coming out of his ears prior to them being slapped by Mr. Gower.
Continuity mistake: Just after George's brother comes home, George is walking across the street and a man is approaching him, but it's then a woman that passes him, not the man.
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.
