Broken Base: The timeline debates - was it an endless loop, or did history change, and which is preferable? The ambiguouslySurprisingly Happy Ending of the fifth film is either a shocking betrayal of the brilliantly dark setting of the first film or the only thing that salvages the original franchise from falling victim to Angst Aversion.
Fanon Discontinuity: Many deny that the sequels and/or remake exist. The reboot prequel series mostly managed to avert this, with Dawn and War in particular being seen as the only films to rival the original.
"Take your stinking paws off me, you damn dirty ape!"
YOUMANIACS!YOU BLEW IT UP!!!
"A planet where APES evolved from MEN?!"
"That is/is not Ape Law!"
Sequelitis: Until Dawn, no sequel had nearly as warm a reception as the original (Rise coming the closest), with Battle at the bottom.
The Novel:
Adaptation Displacement: Few people (at least outside of France, and even then) are aware that the first film was an adaptation at all.
The TV Series:
Germans Love David Hasselhoff: It was much more successful in Britain than at home (although it took until The '90s for the series to get a network screening - in its initial run and repeats thereafter it was shown in every ITV region except STV (Scottish Television, in Central Scotland); Channel 4 gave it its first UK-wide airing in the mid-90s, and both the series and the Compilation Movies regularly turned up on cable TV).