Who's the 'fake Vincent' in the jail?
I thought the guy with the tattoo looked like Val Kilmer. He was the guy Arnold looks at first and seems to think is Vincent. I don't see him in the credits on IMDB, but he may be listed on the movie credits (I didn't bother looking).
Actually if there was a gene experiment in real life, it's sensible that Vincent being the "crap genes" would turn out kind of like Devito's character, but I think he would look a bit more like Julius. Vincent wouldn't have been as funny, but just saying.