Visible crew/equipment: When Mary leans across the drugstore counter to whisper in George's bad ear, there is a small piece of tape on the edge of the counter right in front of her hand, presumably to show the actors where to position themselves for the shot (the tape isn't visible in the other shots showing that same section of the counter). (00:06:55)
Continuity mistake: While George is sprinkling coconut on Mary's ice cream he notices the telegram, and when he picks it up we see the lines of the message as well as the folds in the paper. In the next closeup the lines of the message and the paper's folds are entirely different. (00:07:15)
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: 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: In the scene where Violet and George talk about going up to Mount Bedford, they start their walk down the promenade, close to the intersection where Gowers Drugs and The Bijou theater are visible in the background, along with a tree with no visible branches and a Caucasian couple seated on a park bench facing screen right. At the cut to the closeup, they have moved about 50 to 75 feet further down the promenade, the drug store and theater are no longer visible, the tree behind them now has a branch, the couple is now African American and the park bench is facing screen left. (00:41:30)
Visible crew/equipment: When Sam and his wife get into the car (heading to Florida) George and Mary watch as they drive away, and just as the couple turn around the actor's chalk T-mark is visible on the ground near George's feet. (01:07:10)
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: 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: After George shows the bank examiner the newspaper and tells him about Harry's honor, George leads Mr. Carter to his office while holding the pipe in his left hand, but it cuts to the semi-closeup and the pipe is suddenly in George's right hand. (01:18:45)
Continuity mistake: When Billy is at the bank to make the deposit he writes the date on the slip, and as he starts to take the cash out of the envelope he's still holding the nib pen between his fingers (behind the inkwell), but in the closeup the pen is gone, then in the next shot it's back between his fingers. (01:19:00)
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: After George retraces Billy's steps before he went to the bank, George yells at Billy that he will not be the one to go to jail, and when Billy starts sobbing his right arm is over his left in the wide shot, but in the semi-closeup it's the opposite way, with Billy's left arm over his right. (01:24:20)
Continuity mistake: After George rails at Uncle Billy for losing the bank deposit, when George gets home he removes his scarf and Mary tosses it onto the table beside the telephone. The scarf is still there when George and Mary head to the kitchen, but then it's suddenly gone and it's not on the floor either. Also, Pete jumps off the chair and is behind his parents, then two shots later jumps down again from that chair. (01:25:10)
Continuity mistake: After Clarence saves George from suicide, while they're both inside the bridge tollhouse, a photo suddenly appears tucked behind the thermometer between the two windows which was not in the first interior shot, and then it keeps disappearing and reappearing during this scene. Other changes occur within these shots, such as the window shade to the left of the door and Clarence's book position on the line. (01:39:50)
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: 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 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: While Clarence and George are at the Pottersville cemetery George asks about Mary, and in the shot facing Clarence he's holding his book upside-down with its spine facing him, but it cuts to the closeup and now the book is right-side up, with its spine facing the opposite way. (01:59:20)
Revealing mistake: When George is on the bridge and says "I wanna live again", and Burt drives up, in the shot where George hugs Burt, then Burt pats him on the back, you can see Burt's handprint in the fake snow that was used (a mixture of foamite soap and water) on the back of George's coat. (02:02:35)
Other mistake: Clarence tells George that his brother died at the age of 9 because he wasn't there to save him from falling through the ice, but when you see the tomb stone, it shows Harry Bailey was born in 1911 and died in 1919. That would make Harry only 7 or 8 years old.
Answer: It was a common phrase at the time, like someone saying "oh boy!" or "hot damn."