Character mistake: Mia's Sea-Monkey, in a vertical position, was shown sinking to the bottom the jar. It isn't clear if the Sea-Monkey was dead or if Mia was referring to it when she said, "She's gonna freeze to death, Aiden", but Mia should have known how to properly care for her Sea-Monkey (or refer to the instructions) and, realizing the room was too cold, should have done something - such as wrapped a towel/blanket around the jar and/or moved the jar to a warmer location (e.g, near the fireplace). (01:22:33)
Character mistake: When Tony is talking to the Biancis and others, he refers to victim Kevin Turner as "Kevin Grant" at least two times. (00:44:50 - 00:46:27)
Character mistake: Laura is on the floor, screaming and exhibiting bizarre behaviour, so Dr. Rose Cotter goes to the wall phone to call for help. Instead of maintaining observation and continuing an evaluation of Laura, the psychiatrist faces the wall while making the call and even stares at the wall for a couple of seconds after hanging up. A patient's body language can/do help make a diagnosis, so the psychiatrist should keep her eyes on Laura. (00:11:20)
Character mistake: At the start of the car chase scene the dispatcher identifies the stolen car as an '89 Ford, but the Ford LTD Crown Victoria shown in the chase is a 1986 or 1987 model.
Character mistake: When Annie is in the red truck, she says that she'll be cooking for ten staff. When Alice goes to the beach, she tells Bill that everyone has arrived except for Annie. Even if she had arrived, there would only be eight of them: Christie, Annie, Ned, Brenda, Jack, Marcy, Bill, and Alice. Two shy of what she told the truck driver.
Character mistake: The Fifth Amendment Double Jeopardy Clause does not apply. Libby could be convicted of 1st Degree murder when she gets out and pursues Nick. It doesn't really matter to the plot, however, because it was what Libby believed to be true and motivated her. Further, she ends up shooting Nick in self-defense. So it's all good.
Character mistake: Joe Dirt mistakenly refers to his 1967 Plymouth GTX as a Road Runner while talking to Jill at the carnival.
Character mistake: When Spade leaves Brigid in her hotel room, he says he will buzz her buzzer long-short-long-short, so she will know it's him. When he does return, he only buzzes long-short.
Character mistake: While sitting on the bed, Darkly relays the story of how he got his name, saying it comes from 2 Corinthians 13:12. It, in fact, comes from 1 Corinthians 13:12. (00:10:55)
Character mistake: Mike, despite being an experienced logger, is filing his chainsaw blade in the wrong direction. Also, he's seen filing the teeth of the blade way too many times.
Character mistake: When Ramathorn and Farva pullover the Plymouth Voyager, Ramathorn radios in and says they have a Plymouth Voyager, Vermont plates Alpha, God, Mustard, 1, niner, decade, china. When Farva gets out of the car to call the driver a chicken f**ker, you can see the licence plate, Vermont plate '1 9415'. Ramathorn radioed in the wrong licence plate number.
Character mistake: When Leon goes to see Susan Hoff with his photography portfolio she tells him he needs improvement. After she leaves, Leon tells Jurgis that he thinks she hated his work and Jurgis tells Leon "when she hates somebody's work she gives them about a minute, you got three." In reality, she actually did give him one minute almost to the second. (00:06:58)
Character mistake: After Father Flynn has completed his first sermon, Donald Miller comes into the dressing room and says "That was some sermon, Father." Flynn then says "Hi Jim". Jim is the name of the other altar boy. He should have said Donald.
Suggested correction: Flynn says "hey, Champ", not Jim.
Character mistake: There are some musicians at different times in the movie. One of them is playing a moraharpa (traditional Swedish instrument, a predecessor of the nyckelharpa), but holding and playing it incorrectly. (00:38:37 - 01:39:45)
Character mistake: Leland Palmer handles Laura's body without any gloves when wrapping her and disposing of the body. As with any respectable FBI investigation, upon finding her body and checking for fingerprints, they should've connected Leland to Laura's death within days. (02:05:00)
Character mistake: The first victim gets smacked in the face by the Mistress, and then in subservient fashion holds her hand and kisses it asking if she hurt her hand hitting him. Thing is, she slapped him with the right hand and he is kissing the left better. (00:01:40)
Character mistake: The conductors on Michael's train repeatedly call the seat check slips "zone stubs." Michael could make this mistake, but no conductor would.
Character mistake: When William finds the footprints on the ground after the body is found in the blood vat, he tells Adso that they were twice as deep as they should've been because the person who made them was weighed down by the weight of a body. Adso points out that the footprints were going away from the vats, to which William rebukes him and says that the man who made the prints was possibly dragging the body. If that was so, the footprints would not have been so deep, as the person moving the body would not have been weighed down nearly as much by dragging one along the ground. William is a learned investigator who shouldn't have made such an obvious mistake.
Character mistake: After Clinton's phone call, Christine talks with her assistant and making fun of the "mourning", she says "We went directly to Streisand's opening at the Sands right from the cemetery." However, in Vegas Barbra Streisand never performed at the Sands; she did the International (then Hilton) and the Riviera. (00:05:15)
Character mistake: During the photo shoot scene in Times Square the model actress Lisa calls the other model by her real name, Darlanne, instead of her character name Lulu. It happens when she is pulling her hair for the photos.