I always thought Grosse Pointe Blank worked as a pseudo-sequel to Say Anything…. Lloyd Dobler, who doesn’t want to buy, sell, or process anything for a living, becomes a contract killer. One centers around high school graduation, one centers around high school reunion. John Cusack becomes John Cusack.
Obviously, not really a sequel, but resonant.
[QUOTE=Stephe96]
According to the IMDb, Die Hard is technically a sequel to the 1980 Frank Sinatra movie The First Deadly Sin. Both movies were based on novels by Roderick Thorp. By the way, it also says that Bruce Willis made his movie debut in a walk-on part in the Sinatra flick. Weird.
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Wrong Sinatra flick. *The Detective * was based on the Thorp novel. *TFDS * was by Lawrence Sanders.
[QUOTE=RealityChuck]
Coming to America is a sequel to Trading Places, since Ralph Bellamy and Don Ameche show up as the Duke Brothers from the earlier movie.
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That wouldn’t work because Eddie Murphy plays vastly different characters in both movies. I just saw the Duke Brothers cameo in Coming to America as an funny joke.
Tron → Terminator → Matrix → Dune
It all makes sense. 
[QUOTE=ZipperJJ]
Are Chasing Amy, Mallrats and Jay & Silent Bob Strike Back sequels to Clerks? Or are they more just “movies all having characters that exist in the Kevin Smith Universe?”
Jason Mewes and Kevin Smith appear as Jay & Silent Bob in all four, but other actors appear in different roles (most notably the fella who starred as “the clerk” Dante in Clerks) in all of them.
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They all take place in the same universe, if you listen to the random pointless conversations people have in the movies, they make references to events in other movies (or, in at least one case, to events only MENTIONED in other movies, such as the death of the girl in the pool mentioned both in Mallrats and Clerks). Lots of the actors get used to play different characters in different movies (which gets really confusing in J&SBSB when you see both Brodie (Mallrats) and Bankie (Chasing Amy) show up, one of them suggesting that J&SB stop the movie, the other insisting that they shouldn’t stop the movie.
Then again, you have Ben Affleck and Matt Damon showing up, playing themselves, making a reference to playing characters in Dogma :smack: (evidently in the View Askewniverse, Kevin Smith made a movie about the events that happened in Dogma 
)
A Streetcar Named Desire shows the later years of Scarlett O’Hara (never mind the time gap), after she lost Tara/Belle Reve in the Panic of 1893/Great Depression, and had to move in with Suellen/Stella.
[QUOTE=alanak]
That wouldn’t work because Eddie Murphy plays vastly different characters in both movies. I just saw the Duke Brothers cameo in Coming to America as an funny joke.
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It was, and the fact that there are two characters who look like Eddie Murphy is just a coincidence. Coming to America is a sequel because it shows the Duke brothers starting to regain the riches they lost.
At he end of ** Animal House ** the captions at the end show that Niedermeyer was " Shot by his own troops in Viet Nam, 1969 "
In **Twilight Zone - The Movie ** an American soldier in Viet Nam talks about Neidermeyer getting fragged.