When Angela tells Wayne over the phone that she can't come over because she has to wash her hair, he tells her that he will wash and blow-dry it for her. But blowdryers didn't come into use until a few years later. (That's why washing hair was considered a valid excuse to stay home -- because setting, styling, and drying were so time-consuming. The big selling point of blowdryers was that they would substantially speed up the process.) Trivial point, I know ... just made me feel clever to have noticed :D !

Doesn't Fred Savage have the most expressive face? He communicates so much of what Kevin is experiencing without a word.