Continuity mistake: When George comes downstairs to eat with his parents, there's a lot of commotion including a barking dog. George looks down at it and the scene cuts instantly to a wider shot. He is no longer looking down.
Continuity mistake: When George is trying to open the gate to Mary's house, the walking stick in his right hand is pointed up, but the next shot it's pointed down.
Continuity mistake: The walking stick carried by George as he wrestles with opening the gate to Mary's house is raised up in the closeup shot, then immediately down in the long shot when he finally is able to open the gate.
Continuity mistake: In the run on the Building and Loan scene, Ernie approaches and stands close to Mary's left shoulder, but the long shot of George confronting the crowd shows Ernie further away from Mary and partially hidden by a column in the office.
Continuity mistake: In the drugstore scene, young George is holding up his latest issue of National Geographic magazine for Mary to see, but the next shot shows George bending down to fill Mary's ice cream dish.
Continuity mistake: When Violet is leaving for New York, right before she says "I'm glad I know you George", the scene cuts. This is the same camera angle as before so the scene appears to be an edit splice. The jump cut is obvious. The reason for the rough edit is that a short sequence was cut where Violet asks George to run away with her to New York. It doesn't excuse the jump, but does help explain it.
Continuity mistake: On the day before Christmas, George is showing a couple guys the newspaper about Harry being decorated by the President. The paper goes from being folded in half to open depending on the angle.
Continuity mistake: At the beginning in the soda shop, the first little girl (Mary) is facing toward the camera, away from the other girl that comes in. When they start talking however in the next shot, both are facing outward.
Answer: It was a common phrase at the time, like someone saying "oh boy!" or "hot damn."