Revealing mistake: Throughout the cockpit scenes, Otto's (the auto pilot) face is just painted, with no facial features sticking out. When he is about to fly the plane, he winks out the window, and turns his head. After he turns his head you can see the extra attachment on his left eye used for this. (01:22:40)
Revealing mistake: When the doctor is removing the eggs from the woman's mouth, he actually has them in his hand, not taking them out of her mouth. A simple sleight of hand, but still noticeable.
Chosen answer: All of his questions to Joey are filled with homosexual innuendos; the perverted captain is trying to see if Joey has any such tendencies. In a Turkish prison, men who are sexually frustrated will resort to "companionship" with other men (even forcefully). Movies about gladiators depict ripped, muscular men, and the question about seeing a "grown man naked" obviously fits the pattern.
The gladiator reference is about Spartacus. There is a scene in there about homosexuality.
What scene are you talking about? If you mean the "snails and oysters" scene, that was not part of the movie until it was restored in 1991.