Ghostface tells Gale that they have never spoken over the phone before, but this would seemingly be impossible for the killers to know and something only Gale would know. Given that the killers had extensively researched the previous murders and Gale had written several books about them, as well as given television interviews, they could have learned through them that she had never been on the receiving end of the "Ghostface" phone calls.
(at around 1hr 45m) When Sam is stabbing Ethan and jumps off, the multiple stab wounds that Sam had dealt don't appear on him for a split second until a later scene when he's covering it.
When Samantha uses the knife on the final suspect, you can clearly see the prop blade retract repeatedly.
Despite taking place one year after the events of Scream (2022), which supposedly was during October, and only days before Halloween, all trees and plants in the city are vibrant green instead of orange, red, or brown. Gail's balcony even has outdoor plants that would not survive a cold October climate.
Anyone who has been on Hudson Street in NYC knows: (1) The street signs do not look like the one(s) in the movie. (2) For the full length of it, there are no alleys intersecting Hudson--all are regular streets, with names, signs, apartments, stores, etc. The closest landmark that would match this is Charles Lane, which is a couple of blocks west, intersecting Washington Street, and even this is not a deserted alley, but rather, the back of a set of private homes, complete with windows, doors, and garages, so no dumpsters there. It is also one of the few remaining streets in NYC that still has cobblestones.
Despite Ghostface taking a blow to the forehead from a frying pan, none of the suspects at the end of the movie show the resulting bruising/swelling that would have occurred.
Nancy Loomis looks as depicted in Scream 2 on an archive photo on a police board along with the rest of the previous Ghostfaces, but she underwent a major weight loss and a cosmetic surgery by that time specifically to stalk Sidney Prescott unnoticed as Debbie Salt, so she's unlikely to have posed for a photo at that time, and it would make more sense for the police to have a pre-Debbie picture.