Kilmer was notoriously difficult to work with on sets*
So much so that one director (forget who) famously said, "I wouldn't cast Val Kilmer if I was filming the Val Kilmer Story"
*I've heard this multiple times but never heard it elaborated on was it:
Lead Actor Prima Donna? "I'm a mega star and demanded to be treated like one"
Screaming and rude to other cast and crew, just a generally arse?
Ed Norton style meddling? "I'm the actor but I'm also going to direct and edit the film too"?
Party animal who shows up drunk and/or high?