
Plot hole: When Miss Scarlet tells the other guests, they can pay her in government information, she forgets Mrs White is the only to have no connection to the government and thus can't pay her that way, nor does she have any more money like the others.

Plot hole: The movie establishes that the FBI has a list of suspects thanks to security camera footage from the area where the victims were found. "A red headed man, two African Americans above average height, a white haired man." Then, the zinger; "a man in his 30s with a tattoo of a rabbit or an animal on his right arm", which of course is our guy Josh Hartnett. We see the tattoo, and it's a little doodle of a sheep, about a couple square inches big, below his wrist. That doesn't really make sense; if they have security footage with that level of detail, one wonders how could the rest be so vague. The next entry mentions "a male with a scar on his jaw", which is even more absurd. Either the security cameras picked those details up along with the suspect's full appearance and mugshot, or they just can't know with such certainty (if the suspect was masked or concealed in any way, then they would know for sure it was the killer and wouldn't be chasing people with wildly different appearances).

Plot hole: It seems unlikely any mental institution would let a patient out to visit home for any length of time as happens in the movie with the killer and his mother.
Suggested correction: Unlikely, but still possible. Almost every workplace has a situation in which a person is bending the rules.

Plot hole: Tony said, "If Danny beat him [Kevin] any more, he would have never lived" and Kevin spent a month recovering in the hospital. Tony and Danny were "advised to take a plea" and agreed to 10-25 years in prison. When Kevin went to the correctional facility to "forgive them in person", Kevin said, "We never properly met. I was in the hospital during your trial." Guilty pleas do not result in a trial and a felony criminal case would not be resolved within 30 days of the commission of the crime. (00:44:50 - 00:49:06)

Plot hole: When Holmes starts the human chess game, he says, 'Who had entered the lists, the king's pale knight.' This refers to moving the white knight of the king's side. However, the ritual does not mention to which square it should move. Still having three possible squares to move to (since the knight is on its initial square and the game has already started), Holmes knows and indicates that the knight (Dr. Sexton) must move to square F3.

Plot hole: In the first film, the shape of the ring was a little different and it was set in a ring. Also, it was given to Xania. In the second film, she was never even acknowledged as donating it to the museum.

Plot hole: The movie at best is being dishonest with the ending of the chase scene; to keep Dr. King as a possible suspect, the gunshot happens so shortly after she went out of frame (with no cuts) that (since she is -NOT - the killer) there is no possible way that the gun could have ended in her hand. There's also no possible way for the culprit to escape, to find Hassan in the crowd and be there at the perfect moment, etc. (01:16:35)

Plot hole: It doesn't make sense for the prosecuting attorney to agree to accept a guilty plea from Danny for assaulting an officer, possession with intent to distribute, and resisting arrest with no accompanying guilty plea for at least a lesser-included offense of murder (such as voluntary manslaughter). A violent gang member committing an initiation murder while out on parole would be dealt with much more harshly, especially when the murder victim was a high-school-aged teenager and random victim. (00:09:34)

Plot hole: In the scene in the hotel, David sees the victim's head on the floor after the killer left. Later when David is in a hospital bed he is watching TV and the reporter claims that all the heads were in Judd's car. The killer would have had to have gone back into the hotel room to get the head of that victim after David saw it. She would have put it in her bag right away if she was saving them all. The bag was even left behind. (01:12:30 - 01:25:00)

Plot hole: Marion rips the paper into pieces and flushes them down the toilet. We see all the paper go into the toilet. Later when Lila lifts the toilet seat, there's one piece conveniently placed under the seat that couldn't have gotten there.