Originally Posted by Kooshmeister
And Marcus could come and tell Indy they wanted to see him at Marshall despite not working there. Since he's curator of a museum, what likely happened is that Musgrove and Eaton came to him first and asked him to recommend a guy who could help them and Marcus said, "I know just the fellow," and they went to Marshall where he told them to wait in the lecture hall while he went and fetched Indy, who he was already scheduled to meet about the idol anyway.
He could, but I think it's reasonable to think that it was intended for the audience to think that he worked there: this seems to be all a lot of fan bending after the event to try and sort out what just seems like some mistakes made onscreen; or perhaps they just thought Marshall was too much of an in-joke and changed it, but then went back for Skull.
It's also implied that the Government guys came to Indy because he knew Abner Ravenwood as named in the Nazi message; if so they wouldn't have needed to go to Marcus so there'd have been little reason for him to be involved unless he worked at the college. It's all open to interpretation, though.
I appreciate that some largely unseen details do assert that they're different colleges, but for me I find it easier just to think that they're all the same college and that Marcus works there. There's nothing explicit to say that's wrong and it just makes things a little bit more satisfying, especially as the places look so similar which seems to imply that they're intended to be the same place (Darabont seemed to think the same- we see the college museum in City of the Gods full of stuff Indy obtained for Marcus' museum which implies Marcus worked for the college, and Spielberg presumably didn't mind that). Sometimes an error is just a error and a moviegoer has to ignore it: I'm definitely not saying anyone's wrong though; just which scenario I prefer.