Collider posted a roundtable conversation with Spike and Max that includes some excellent anecdotes about the making of the film. Representative excerpt:

Q: Max, how gross was it for you to do that scene where you come out of KW?

Max: You don’t want to know. They put some sort of gross gel stuff on me.

Spike: He was covered and goopy. He hated it. We shot it once, and then we had to shoot another piece of it again, and he just did not want to get in it. He said, “I will only do it if, afterwards, you let me cover you in it.” And so, afterwards, we went back to his room and he just covered me in it. He was so happy and I was miserable, so it was a good retribution.

Yeah! That’s the way to deal with adults.