Character mistake: When Woody Harrelson picks up the movie magazine and opens to a page, he says "I love Clara Bow." The picture he is looking at is of Jean Harlow. (01:00:54)
Character mistake: Toward the end of the film, Detective Davis orders Captain McKenna to put his badge on the table. New York City police always refer to their "shields", not badges.
Character mistake: Detective Spitzer went into Harper's dark/unlit house, saw his partner Greg on the floor, and then saw Alec standing in the kitchen. Without identifying himself, telling Alec to drop his weapon (pistol pointed toward the floor), or bothering to determine what happened, Detective Spitzky shoots Alec. (01:27:08)
Character mistake: Right at the beginning of the movie, introductory technobabble. "In this canister, there's a solution of protons. The canister is attached to a rotor circuit that generates the protons to the speed of light." I believe the science genius and creator of time travel mixed up the words "generate" and "accelerate" here. (00:00:50)
Character mistake: Queen is an attorney and should know how to conduct herself as a passenger in a car pulled over by police, yet she fails to behave in an acceptable way. Even though certain things may be permissible under certain circumstances, a lawyer should know exceptions and extenuating circumstances, but she apparently does not. She did not have the right to interfere with a police officer and "demand to know" or get out her cell phone to record if she was told to keep her hands where he could see them. (00:10:25)
Character mistake: Shaft meets Junior for the first time and mocks him with the offer of bubbly water. Junior says "And as for that wedge of lime, it makes it alkaline, so..." It wouldn't, since lime juice is rather acidic. (00:23:10)
Character mistake: A guidance counselor/principal told Calvin, "You're a very very smart young man. Perhaps even gifted. Last year you scored in the top ten percentile on the PSAT..." Because Calvin deliberately "blew" the SAT, the school official was going to make arrangements for Calvin to retake it. But this would not be necessary. The PSAT score (out of 1520) is considered equal to the SAT score (1600). The school official would be more helpful by getting Calvin admitted to college using the PSAT score. (00:08:35)
Character mistake: Casey is sixth of six male students standing in a row to individually demonstrate a karate move for Sensei. After the fourth student, Sensei passes up student #5 and says, "Next. Casey." Sensei completely missed the fifth student, the only other beginning white belt like Casey. (00:28:45 - 00:29:10)