The 'mistake' slide in art history class?

I assumed that she simply got a vacation photo mixed in with the class slides. She didn't actually look at the slide until the student asked what it was. I think the sequence was just a throwaway joke.


Movies I've Seen: http://imdb.com/mymovies/list?l=25003655

The idea is that Huston's character is trying to make the students question their definition of 'art' by asking if various paintings/photos could be considered art. But, the piece that most questions the standard definition of art (a simple snapshot) is a mistake. It's a comment on how art teachers pretend to understand all forms of art and to be open to looking at any work as a piece of art, but actually completely disregard any artwork that doesn't have some sort of novel value. More direct pieces of art like the snapshot and Jerome's drawings are treated like *beep* while gimmicky works like Jonah's or Eno's paintings are looked at more seriously.

If you look really closely the man in the picture is professor David Zipkin, the one who is on stage with Marvin Bushmiller. Huston's character was probably involved with him but didn't want the students to know. That was my interpretation.