In the final scene where Judge Hardy raises the roof on Andy's convertible and
crushes his top hat, there are a couple of goofs. First, the button he pushes
to raise the roof is to the right of the driver yet just a few minutes earlier, in an identical car, Andy pushed a button to raise the roof and it was on the left. Second, the top hat Judge Hardy is wearing is shiny and new. But after it's flattened, it's replaced by an old beat-up version that is noticeably different. Obviously rather than damage a good top hat, they simply switched the hats between takes.
When the school principal announces the class standings (at 1:10:34) and Andy confesses his failing, the students seen seated in the second row changes between the closeup of Andy (seated) and the long shot of the class.