Patti Forte - Will Forte's real life mother - played Patti Miller in the episode "Alive in Tucson". Patti Miller was the mother of Phil Miller, and was shown during a flashback on one of Phil's past birthdays. In the show, she was explained to have been deceased by the virus.
In the episode "Some Friggin' Fat dude" Melissa mentions that "The Shawshank Redemption" is her favorite movie. She later mentions "The Godfather" is "like my second favorite movie". Those are the top two rated movies in the IMDb top 250 movies of all time.
In season two, Will Ferrell guest stars as Gordon. We later find out that Gail (Mary Steenburgen) dated him in the show. Steenburgen played Ferrell's step mom in the movie Elf (2003) as well as mother in the movie Step Brothers (2008).
There's been a recurring gag ever since the beginning of season 2, where a famous guest star is brought in and is killed off almost immediately with only one line of dialogue: -Will Ferrell as Gordon (season 2, episode 2) dies from a heart attack after being scared by Carol. -Jon Hamm as Daryl (season 3, episode 1) is shot and killed by Melissa. -Jack Black as Rear Admiral Roy Billups (season 3, episode 1) is shot and killed by Pat.