This is a very minor nitpick, but why are there helicopter noises at the start of Happiest Days of Our Lives? Other than Rule of Cool?
You got me. But in The Movie they are replaced with the train sounds, which make sense in context, at least.
I think they put the sound as a segue from Another Brick in the Wall (Part 1) to Happiest Days of Our Lives, because it was supposed to represent Pink's father dying at war, but that's just my opinion. I'm sure The Other Wiki has some info on this.
The teacher was in the war. It gets more into this in a couple songs on The Final Cut.
Probably to illustrate the oppressiveness of the education system that Pink goes through, as the train Pink sees passing by him in the tunnel filled with putty-faced passengers in the movie with intercuts of the teacher saying, "Hey! Yes, you! Stand still, laddie!" is supposed to do the same.
Other strange transitions: telephone sounds at the end of "Another Brick in the Wall Part 2," and airport sounds between "Goodbye Blue Sky" and "Empty Spaces." What do they mean?
The telephone sound effects are Pink trying to get through to his wife and failing. The airport sound effects might be Pink going from London (on the bad-ass Concorde, no doubt) to Los Angeles for a gig.
This is more of a nitpick on the movie. After Pink teared down the wall where did he go? Last we hear of him is during the wall's collapse he screams.