Most of those guys -- Leslie Nielsen, Peter Graves, Robert Stack, probably a few more I'm not thinking of -- didn't quite "get" the idea of parody. They were "serious" actors and came from a certain school of thought, if not actually the same acting school. ZAZ had to explain to them that they just play it straight. Characters in comedies don't realize that they're in a comedy, and that's what so funny. And that's why ZAZ wanted them. I wouldn't be surprised if some of those guys still didn't understand why it was so funny. Leslie Nielsen eventually did, because he played the same type of character pretty much from that point on, but I remember reading that Peter Graves had some serious reservations about the dialogue between Captain Oveur and the boy.