Kevin Spacey, K-PAX press conference. 2001
The soft-spoken actor talked about those banana peels. “If it was just banana peel, I could answer this question briefly, but it was a lot more than that,” Spacey said. “It was always in the script that that’s the way Prot ate produce; he thought all of it was good. If you gave him a coconut, he’d probably eat the whole thing.”
The actor said when the day came to shoot the scene with the bananas, the prop department had crafted fake peels and put a banana inside it.
"No offense to anybody, it looked really bad. Just to the naked eye, it looked like a gigantic yellow felt marker, and it fell apart," he said, chuckling.
He had the staff go to the store and buy some really nice, ripe bananas and wash them. Then he ate them. He was never specific but said he ate more than 10, and they were horrible.
"It was an astounding potassium high; you’re bouncing off walls," he said. "Those scenes with Jeff, the look on Jeff’s face is the look on Jeff’s face. He couldn’t believe I was doing it."