Factual error: At the climax of the movie, Alice swings the machete at Mrs. Voorhees and decapitates her. When the blade makes contact with Mrs. Voorhees' neck, her head flies off at an incorrect angle, as though the cut began on the opposite side.
Factual error: When they go into the water, they put mouthpieces in, but, a few times, they talk to each other, which is impossible with mouthpieces in.
Continuity mistake: When Norma and Helen are in the salon, and they are talking about Carrie going to the prom with Tommy, Norma is getting a fancy hairdo done for the prom. But in the next gym scene, she has her plain braids and a cap on. (00:48:20)
Suggested correction: When you watch the movie leading up to that event, it's obvious that Norma is a tomboy, and is always wearing a ball cap and wearing her hair like that. It's who she is and perhaps decided after her hair was done that it didn't feel right and decided to go back to her look.
Continuity mistake: In one of the last scenes, Cate Blanchett is standing in the doorway of her son's room. She is wearing a blue striped dress. When she walks into the room, she's wearing a floral dress.
Other mistake: The construction of a staircase does not require a large nail at the site shown on the steps. Furthermore when Emily snags her clothes basket on the stairs it lifts a small nail up. How did it grow into a 2 inch fat nail?
Revealing mistake: When the team descends to the bottom of a hole and one female member is first wounded and then dies. After checking her pulse, the others pronounce her dead and begin moving out. As the last one is leaving, the "dead" actress lifts her head up off the ground and looks left. (01:13:10)
Factual error: How would the creature be able to re-enter the ship by climbing into the reactor piping? The reactor fuel system is not open to the living space of the International Space Station.
Visible crew/equipment: There is a shot of Holly crawling through a tight space with the camera facing her moving backwards as she crawls forwards (about 30 minutes into the film). In this shot, the wheel marks of the camera can be seen on the ground in front of her. (00:30:05)
Continuity mistake: In the end, when Michael has grabbed Karen's ankle and is trying to pull her down into the basement, Allyson grabs a knife off the floor and stabs him. However, if you watch very closely, you can see she's already holding the knife in one shot before she grabs it. (It's the shot right before Laurie screams "I've got you!" to Karen.) You have to pay attention because it goes by quickly, but you can see Allyson lifting the knife into frame for a split second, even though she doesn't pick it up off the floor until about 15 seconds later.
Character mistake: Selena Gomez drives into town in a fully restored 1967 Pontiac Le Mans, which is a long box shaped car. However, when confronted with Bill Murray and Adam Driver, Adam Driver complements her on her 1968 Pontiac Le Mans, which is a completely redesigned shorter curved body style. The two look nothing alike.
Revealing mistake: When Brom (disguised as the horseman) throws the jack-o-lantern at Ichabod, there is a shot from Ichabod's perspective showing the jack-o-lantern flying toward him. It jiggles from side to side, revealing it was travelling on a wire.
Plot hole: When the cop shows Pam the newspaper clippings they include what look to be fresh photos of the real Jason from the events of Part IV, yet no photographer is ever seen taking pictures of Jason alive in the previous films and most likely wouldn't live long enough to publish the photo. (01:25:00)
Suggested correction: The picture was taken from security footage at the hospital after killing the 2 employees.
It was never shown.
Visible crew/equipment: As Rick and Chris get in the Volkswagen Bug after Shelly returns it, you can see three crew members in the backseat window reflection. (00:35:55)
Continuity mistake: After Sarah and Rios come out from the flooded cave, their clothes are bone dry even though there were almost fully submerged underwater. (01:01:25)
Visible crew/equipment: When Freddy falls over the banister onto the stairs near the end, notice the crash mat he lands on. (01:18:55)
Plot hole: Peter goes into Carl's mind to save Catherine. When he's in there he sees the tank with the water nymph. On the tank are strange symbols which provide the FBI with the clue needed to find the latest victim. Makes sense so far. But, go back to the scene just after the FBI have captured the comatose killer and are looking in his basement. The FBI are looking at the contraption that the killer uses to suspend himself over the victim. On the contraption is the same symbol seen later on the water nymph's tank. Why didn't the FBI follow up the symbol then?
Plot hole: When Bridgette ran through the glass and Linda and Jim were at the hospital Jim tells Linda he called her mom and told her what happened and she was coming to stay over the next day. Yet apparently her mom forgot what happened because she had her committed because Linda didn't remember what happened to Bridgette's face. Also, Bridgette was like 9. How come no-one just asked her what happened?
Continuity mistake: During the paper cut scene, when Bella is thrown against the table, there are 5 vases of flowers and 3 sets of candles. After she hits the table she lands against one of the vases and knocks the 2nd one to the floor, but the next shot shows only one vase left upright. (00:14:50)
Continuity mistake: When Hauser picks up the Admiral, after the Brain Bug attacks them, she has no yellow alien blood on her as she's being pulled up, but when the shot changes, as she's standing up, she now has blood on her face and uniform.
Factual error: The moon is full every night the highschoolers are at the lake house.
Suggested correction: Sorry to burst your bubble here but there is scuba equipment which allows for talking whilst using a regulator.
They're not wearing such equipment. In the movie they're just wearing regular mouthpieces.
In the DVD commentary the writers explain that the divers should have been wearing full face masks which allow for communication, but the director changed it for mouthpieces, but kept the talking in. They pointed out this mistake.