Recently, my parents showed Finding Nemo to Brendan (in two sittings, but that's irrelevant). The beginning part, where Nemo loses his mother, is pretty traumatizing!
As a result, if you bring up the movie with him, he'll say "mama, mo?" (mo, as in "not have"), and he'll have a worried expression on his face.
I think this is one of the reasons why he wouldn't let Cat leave the table during our buffet breakfasts and lunches during our cruise.