Old Shame: None of the main human cast members had any major success after ALF, and all four actors playing the Tanner family have since retired (possibly as a result) from acting. Max Wright wanted nothing to do with the show for a long time afterwards, but later changed his mind, acknowledging in interviews how much joy ALF (the show and character) has brought to the world over the years.
Screwed by the Network: NBC promised that even if they canceled the show, they would make sure there would be an episode to resolve the Season 4 cliffhanger; they went back on that.
Troubled Production: It has been described as being what Hell would be like for actors when they die. Due to the constant arduously technical demands of making the ALF puppet come to life, to film a 22 minute episode it took 20-25 full hours. It was incredibly demanding, and reportedly almost everyone on set was miserable.
What Could Have Been: The last ALF comics issue ended with a No Fourth Wall story where ALF presented snippets of stories that would have been seen in the comic if it hadn't been canceled. Highlights include a Thelma & Louise parody with Kate and Dorothy, a Melmac version of the Watchmen called "The Washmen" (superheroes who run a laundromat), the revelation that Lynn would move out and get her own apartment, and a story where ALF and Brian go for a ride in ALF's spaceship and end up getting lost in space.
Word of God says that had ALF gone on for a fifth season, the setting would have been changed from the Tanner home to a military base. Somewhat reminiscent of The Phil Silvers Show, new episodes would have focused on the military trying to keep track of mischievous ALF in the same way the Tanners did for the first four seasons. The concept was later reworked into the Made-for-TV MovieProject: ALF.