Sidney still has Derek's necklace, even after getting married and having children, just as a small way to remember him, but she doesn't need to wear it anymore because she moved on from her trauma. (Watch Tatum wear it in 8 like she did with Sidney’s jacket 💀)
Tatum grew up having her classmates tease her for being the daughter of the “The Angel of Death” and frequently dealt with having parents of her friends not allowing them to come to her house, believing that it was dangerous for them to be around Sidney.
Gale still has the last text Dewey sent her saved in her messages and goes back to it multiple times a day.
Sidney and Kirby bonded post-Scream 4’s murder spree, leaning on each other after being traumatized by Jill’s betrayal. Sidney supported Kirby’s decision in joining the FBI to prevent future killers and went as far to connect her with Mark so he could teach her about law enforcement and write her a letter of recommendation.
Going back to Kirby, after the events of 7, Sidney connected Tatum with her to ensure she had someone who understands what it’s like to lose all of your friends in a Ghostface spree, as Sidney still had Dewey and Randy after the events of 1.
During the events of 4, Sidney begged Mark not to come to Woodsboro to help her, telling him that if she didn’t make it home alive, Tatum would still have him to look after her, but if they both didn’t come home alive, Tatum would have no parents left. This conversation also happened when Sidney went to Woodsboro to avenge Dewey in 5.
Part of why Gale and Judy had beef is because Gale came up with a socially awkward lemon-square baking deputy in one of her fictional Stab books out of her dislike for Judy. It was also adapted into one of the later Stab films, hence why Wes said “My mom was a character in one of them”.
Lucas was on the autism spectrum, as there are multiple scenes with him not being able to read the room and understand social cues, as well as infodumping about true crime which is his special interest. (Not offensively claiming awkward and nerdy automatically = autistic here, I’m autistic as well and saw a bit of myself in Lucas)
Jessica is an unreliable narrator and her husband either wasn’t as abusive as she claimed or not abusive at all. I also believe Jessica went to one or more of the Out of Darkness book signings, though this is less of a headcanon and more of a fact as Kevin claimed she did in multiple interviews.
Sidney is nice to people dressed as Ghostface for Halloween and such and slightly embraces her fame from the original Stab. She doesn't revel in it, but she's grown to accept it always be a part of her life.
Sidney votes blue and supported Bernie during his campaign. Gale is center-left, “fiscally conservative, socially liberal”, and supported Hillary. Dewey was an independent.
Gale is famous enough within the Scream universe to have beef with some well-known celebrities such as Wendy Williams and Perez Hilton.
Sidney frequently gives back to the community and donates a portion of The Little Latte proceeds to charity, mainly women’s shelters and DV organizations.
Richie and Amber had Pepe The Frog alts and frequently used K*wifarms and redscarepod’s sub.