When Jason is running back to his house after his first time working his face is clean. When his mother goes to check on him his cheek is dirty.
When the Carter boys walk to school around the 13 min mark, it appears that the fly is open on Jason's pants.
When John Carter carries the birthday cake to the table, one of the candles is not lit.
The boys' pants have belt loops, but belt loops were not invented until 1922.
No loving mother would reject a little child's gift and break his heart like Sarah did.