Edward Furlong confesses it was "scary as hell" filming the scene in the gritty prison drama Animal Factory (opening in select cities Friday), in which his character is raped by

Tom Arnold's. Actually, prior to shooting, Furlong couldn't understand why actor-director Steve Buscemi chose the affable comic actor to play his attacker.

"You put Tom Arnold in that situation, and [he's] a scary-looking guy — he can be big and ugly and psycho-looking," the 22-year-old actor tells TV Guide Online. "But in life, he's very nice; he's very sweet."

The former T2 star says it was also strange working with oddball actor Mickey Rourke, who spent two days on the set of Animal Factory, playing a cross-dressing prisoner. "I didn't recognize him at all," he says. "I remember the read-through we did; everybody was saying, 'Mickey Rourke was so good.' I was like, 'That was Mickey Rourke?!'"

During the shoot, Furlong found himself trying to keep up with the eccentric Nine &#189 Weeks star as he continued to drift from the script. "A lot of it is just stuff that Mickey Rourke made up," he says. "He'd blurt out something like, 'Come eat my p---s,' and you have no idea what to say."

By comparison, working with the movie's real-life prison extras was easy. Furlong says his initial concerns for his safety quickly vanished as he got to know the inmates on location at Pennsylvania's Holmsburg State Prison. "There were no problems," he says. "The only problem was that they always bummed cigarettes off me."