In the classroom scene when Hinckley is talking about the essay papers, the front row of desks is very close to the teacher's desk, maybe about a foot of clearance. When the bell rings the camera angle changes to a mostly head-on shot of the desks and the gap between them and the teacher's desk is much wider and multiple students walk through it without issue. The camera angle changes again to a side-view and the desks are again much closer together.
When the bad guys arrive at the building after they leave the circus (just after Ralph is fired from the canon), they leave the side door of the van open and they walk into the building. When Ralph looks down from the roof of the building and spots the van a moment later, the side door is closed.
Film crew is visible in the hubcaps of the red VW.