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. (01:17:35)
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: 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. (00:35:20)
Continuity mistake: When George first finds his brother's grave the death date is visible, but after arguing with Clarence he has to wipe snow from the base of the stone to reveal the date. (01:58:35)
Continuity mistake: When George is giving Violet the character reference and loaning her money, the pipe suddenly disappears from George's mouth. (01:21:50)
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.
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.
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. (00:09:25)
Continuity mistake: When Bert the cop is struggling with Clarence and Clarence disappears, you can see Ernie's shadow which shows him pointing and gesturing with his hand before he actually does it. (01:56:20)
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: In the scene after Bailey becomes nonexistent and they go to the bar, Clarence and Bailey are thrown out, but when they land they have switched positions. (01:50:20)
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.
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. (01:07:30 - 01:12:40)
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.
Answer: It was a common phrase at the time, like someone saying "oh boy!" or "hot damn."