One of the kids is missing a head, one child has two left hands, some children don't have legs. The Darth Vader mask and shirt don't make sense visually, and you can see the same shirt repeated on the child with no head.

The desks and chairs are inconsistent, looks like there are a few different styles but they also have bits that don't connect to anything. I don't know what it was like in the late 70s but generally classroom furniture is very consistent.

Then there's something really strange going on with the shadows, like the smurf and clown have dark cutouts attached to them that could be shadow but aren't.

I can't figure out what is happening with the Disney princess mask, it looks just pasted in