Continuity mistake: When Kevin goes to the grocery, he buys Tide detergent. While walking home, the two bags break, but no Tide detergent falls out.
Revealing mistake: When Carl is being dragged away by the demons, you can see the cable line that he's attached to. May be fixed on DVD.
Revealing mistake: Near the middle of the movie Samantha Mathis is walking across the high school campus. The name of the high school in the movie is "Hubert Humphrey High School, " but behind her, above the library door, a sign says "Saugus High School Library". Shows better in 4.3 aspect. (00:31:45)
Factual error: Though extremely modest on today's standards, the dress worn by Clara to the hoedown shows far too much cleavage for the time. No schoolteacher would ever wear a dress like that in the 1880s.
Plot hole: At the end of the film, we see Edward carving ice sculptures in his mansion. How did he get the ice up there? First of all, it takes place in a warm climate and I didn't see a freezer up there in the castle. He couldn't have gotten ice from town because firstly he had scissors for hands and couldn't have gripped the ice. And, even if by some miracle he could, he wouldn't be able to buy any from town because everyone in town but Kim was convinced that Edward was dead, she told everyone that they killed each other. And Kim didn't bring it to him because she told her granddaughter in the end that she never saw him again after that night. So where did he get that ice?
Revealing mistake: When the scientists inject the mouse with poison, they put it in a jar. The, after they place it down you can see someone's hand swap the jar for one containing a dead mouse. You can even hear it. (01:17:58)
Continuity mistake: When Ford and Jazz are at the Colleen Sutton party, Jazz is asked to keep an eye on Colleen. Collen spots her and put a CD down her dress with the black end facing downwards. When Ford is taking the CD up from her dress the black end is now facing upwards. (00:43:25 - 00:45:00)
Revealing mistake: When the lawn mower the heroes send off as a diversion crashes you can see a wire pulling it. (01:01:30)
Continuity mistake: When Molly takes Mikey into work and he is under the desk, Rona is still wearing her shoe. Yet when the scene changes, her shoe is missing when Mikey starts tickling her foot. Then when the boss realises that Mikey is under the desk, her shoe is back on. When the shot changes again, her shoe is off.
Other mistake: In the music within the ending credits, the lyrics incorrectly state that Raph is the leader of the group when all Turtle fans past and present know it is Leo.
Factual error: Cher complains that Astroturf is going to ruin baseball. Mermaids is set in 1963 when Astroturf was still being developed under the name Chemigrass. It wasn't christened Astroturf until it made its world debut on the floor of the Houston Astrodome in 1966.
Continuity mistake: When the Drapes are singing to Allison/Baldwin/Mrs. Vernon Williams, the song, "Gee, I Love that Girl" in the speeding cars, Hatchet-Face's gold earrings are on, then off, then on again. They are seen again in other scenes.
Continuity mistake: At the end, when Jack shoots the main bad guy, he had already double-tapped somebody, but then shoots at least 5 more shots from a 6-shot revolver.
Other mistake: When Casey's men are robbing the Triads, Abbott says "Don't move or you're dead." He then turns to his left, and while facing left, he shoots two of the red Mercedes' tires. However, he is standing directly behind the Mercedes, so it would be impossible for him to turn to his left and shoot two of the car's tires.