Star Wars Episode 6: Return of the Jedi - Lando Can't See in That Helmet
After Chewbacca is taken away in Jabba's palace, the guard walks through an entranceway, bonks his helmet, and then pulls it down to reveal clumsy old Lando Calrissian!
I saw that too when I watched it the first time. I also thought about his "disguise" I use the term lightly, because you can tell it was Lando before he pulls his mask down.
You can tell it's him before he pulls the mask down, but this shot is the only one that really shows him close up in the disguise. Also, it's not necessarily a disguise.. he could have gotten hired by Jabba, who as far as we know didn't know or care who Lando was, and then had to wear the helmet as part of his guard outfit. And last of all, people who had seen the previous movie might have almost forgotten about him and not recognized him until they saw his whole face.
Uh... my point was about the fact that he bumps his head. I have another slip-up, but for some reason this site won't accept it. It's when Lando's flying into the Death Star. He knocks the antenna off, and then he says "That was too *cloose*". Nitpicking, sure, but they really could have looped "close" over "cloose" so it wouldn't sound stupid.