First Installment Wins: The original is still the best-remembered of the bunch. Most casual viewers might be surprised to learn that Walter Matthau and Tatum O'Neal's characters are, in fact, not in any of the sequels.
Ho Yay: Lupus and Tanner, especially in the second movie.
Values Dissonance: A definite product of its time, that's for damn sure. The fact that it got away with a PG rating might baffle some people.
The 2005 remake contains examples of:
What Do You Mean, It's Not for Kids?: Despite being a Lighter and Softer remake, the movie is not kid friendly, featuring a lot of swearing, crass and lewd stuff (including the implication that Buttermaker got a stripper joint to sponsor their little league game), and Buttermaker also being implied to have slept with one of his softball teammate's moms.