The series was partially inspired by "All in the Family" (1971).
Steve's original design was much geekier and gawky and he was voiced by Ricky Blitt. Halfway through production, his voice actor changed to Scott Grimes and his design was made to be more attractive, so he would be less comparable to Neil Goldman from "Family Guy" (1999). This design is a caricature of one of the series creators, Mike Barker (III).
Fox showed a viewer discretion warning before airing episode 102 "Threat Levels" due to "Cartoon Nudity".
Klaus's voice is based on Peter Lorre (I).
Steve's friend Snot is based on Booger from Revenge of the Nerds (1984) and is voiced by Curtis Armstrong, who played Booger.
In episode 104 ("Francine's Flashback"), we find out that Francine was 20 in 1985. We can draw from this that Francine was born in 1965, and that in the cartoon she is around 40 years old. This is confirmed in Episode 123 ("Tears of a Clooney"), in which it is Francine's 40th birthday.
Hayley says in "Stan Knows Best" that she is 18 years old. Based on this information, we can assume that she was born in either 1986 or 1987 (depending on what month her birthday is in.)
The headline of the Langley Falls Post that Stan reads in the opening credits is different in every episode.
WILHELM SCREAM: In "Roger Codger", immediately following the explosion of the grenade Stan's new coworker throws.
In some episodes, the opening sequence is shortened severely, and the final few seconds (the flag and the accompanying "Good morning, USA!") of animation is all that remains.
The uniformed officer in the Underdog Productions logo at the end says something different in every episode. (Not unique, just out of a small assortment.)
The final frame of the introduction was changed for seasons beyond the first. At the end of the credits in the first season, all that could be seen was a big "American Dad!" logo in front of the American Flag. In all subsequent scenes, this logo was shrunk to fit the names to the series creators on the same screen.
Hayley's middle name is Dreamsmasher.
Most episodes contain a reference to moths, or feature moths.
