Character mistake: The Rufus hologram states that he first brought the phone booth to the Chosen Ones (Bill and Ted) in 1989, referencing events of the original film. While that was the year the first movie came out, it took place in 1988 (indicated by the opening title card and dialogue throughout the movie).
Character mistake: A radio report refers to a character with two different police ranks with 15 seconds apart in the same broadcast - first as a Police Chief and a few seconds later as a Captain. (00:21:28)
Character mistake: Following the killing of a DEA forensics agent [guy sniped on the boat], a newspaper clipping is shown on screen. Underneath the headline of the article, "Assassinations" is misspelled from omitting an S in the second set of S's. However, if you read the article, you will see the word is correctly spelled in the first paragraph. (00:20:28)
Character mistake: There are signs out front as the Spenglers arrive at the dirt farm. One of the signs is a call back to a scene in Ghostbusters 1984. In the scene, Ray quotes the book of Revelation: "And I looked, and he opened the sixth seal, and lo, there was a great earthquake. And the sun turned black as sack cloth, and the moon turned blood." When Finn Wolfhard reads it he misquotes the line saying "The sun became as black as cloth."
Character mistake: Near the end while in the caves Maggie is the first to go missing, but they use the name Gwen multiple times, the actress' actual name.
Suggested correction: Maggie Q is the actress and she plays the character Gwen Olsen.
Character mistake: When the camera pans to the frame containing the picture of Lars with his departed mother, the caption says "In memory of our beloved mother Mirra Gunnarsdottir", with a plain O. On the cross, her name is Mirra Gunnarsdóttir. It's two different letters, and it'd be pretty strange to honor the memory of your mother printing a photo with her name in the wrong form. (00:01:10)
Character mistake: After the dodgeball game ends Jerry asks the referee if skyzone had a bar, but in the background he's already walking away.
Character mistake: They keep calling the vehicle a milk truck but it says "ice cream" on it. (00:23:55)
Character mistake: John shot at the "werewolf" but wasn't successful in hitting it. Instead of pursuing the werewolf, who he supposedly was determined to catch, he let it run away. Alcoholic or not, a sheriff's deputy should have done everything possible to try to capture the creature that was terrorizing the small town. By not even attempting to follow the werewolf, John missed the one opportunity he - or anyone else - had thus far to potentially put an end to the senseless and tragic murders of young ladies. (00:55:35)
Suggested correction: Dude's daughter was attacked and bleeding from the head, of course he didn't pursue it.
Suggested correction: He didn't go after the wolf because his daughter was hurt, and his (albeit misguided) parental instincts took over. It's not at all a character mistake for him to prioritize making sure his daughter is all right over chasing a perp. Most parents would probably do the same thing.
Character mistake: Dean told Laura that Fiona's toiletry case was in his bag because "She couldn't fit it in her carry-on, so I put it in my luggage." Laura (who had no reason to fabricate the story to her dad Felix) changed the details, which she couldn't know based on what Dean told her: "There were some of his co-worker's toiletries in his luggage. But she couldn't put them in her carry-on for security, so he offered to put them in his luggage." Unable to fit in isn't the same as "for security." (00:13:05 - 00:23:57)
Character mistake: Caseworker Jaylene recognized the man in the photo with Tulsa's biological mother (deceased for two years) but did not know if Tommy was Tulsa's biological father like Tulsa asserted. Jaylene also knew the proper procedures for placing a child (including emergency situations) and that she could lose her license - not to mention be putting the child at risk - by letting her stay with Tommy. Supervisor Kerry even warned Jaylene, but Jaylene left Tulsa with the man "assumed" to be her father. (00:07:05 - 00:12:35)