7. Does Your Sequel Contradict The Earlier Film? Noooooooooooo!!!!!!!
This is so obvious. But it seems to utterly elude production teams and writers. Earlier I mentioned how long ago I was so utterly gutted by "Highlander 2: The Quickening" I almost contemplated legal action. The movie had a lot of problems; Sean Connery's existence governed by the same laws that seem to bring Tinkerbell or Beetlejuice into corporeal being not the least of them. However, the film literally goes out of its way to CONTRADICT the earlier film. Both the rules that govern the Immortals (Who are now aliens, by the way. Uh.....thanks) and the nature of their conflict are revised so as to allow "There can be only one" to become "There can be only one, unless there are others who arrive from your homeworld, in which case everything resets. Like a video game." The changes to the Highlander mythos (Which are thrown out AGAIN by the time 'Highlander 3: Mario Van Peebles' Playdate" arrives) are dumped on you in the clumsiest exposition ever, with actors literally babbling out the lines as though they desperately wish they were anywhere but here and KNOW how nonsense these changes/concepts are. Now that I think about it, that sounds familiar. Oh yeah. That time the Force was rewritten to be space-herpes. Nice. I'm not saying you can't fill in blanks. (For example, "Aliens" creates a pretty elaborate illustation of a corporation that "Alien" only hinted at.) But if you've got Yoda waxing philosophic on the mystic nature of the Force in one film, basically saying it's a "force of nature" akin to magic/religious power....it's gonna be a bit odd when you retcon it as microbiological influence AND that same Grover-voiced muppet just seemingly forgot that. (Honestly, I'd understand if he just hated saying it and wished it was magic.) We fall in love with movies and know that sequels/prequels will add things and developments we may not have added ourselves. But we're more likely to fall in love with them if they don't take that movie we loved and shove in space-STDS, Aliens from a never-before mentioned homeworld that are equal parts "Pee-Wee's Playhouse" and Duran Duran's "Wild Boys" video, or ghost-Hayden Christensen in the special edition (Whoops, that's another article entirely.....). Don't change what you stated in the first/prior film. You'll make everything that comes after harder to love.
In a parallel universe where game shows' final jackpots and consequent fortunes depend on knowledge of obscure music trivia and Jon Pertwee/Tom Baker Doctor Who episodes, I've probably gone rich, insane, and am now a powermad despot. But happily we're not there, so I'm actually rather pleasant. Really.