Plot hole: A central plot device in this episode is that there is no six letter word made up of the letters EXVIN, so the murdered man cheats at the word game by playing a word he knew to be inadmissible - exvin, a wine connoisseur who no longer drinks. Since he is supposed to be a stone cold killer player at this word game, don't you think he would have thought of Vixen? Sara Sidle points that word out later - why wouldn't a world champion word game player have figured it out, using a safe, common word and avoiding a possible challenge?
Suggested correction: If you watch the episode (timecode 00:36:20), in the flashback it shows exactly why he did not use vixen. There were 2 spaces between the "x" and the "n" on the board, so Adam played a bluff and used the fake word exvin.
Other mistake: In the flashback that shows Adam Brenner playing his opponent using the word "Exvin", we can see that the X is also used in "Juxtapose". When the opponent adds an S to "Exvin", he is challenged and made to take back his tiles. However, the X would remain where it is because it is a part of another word. Since the opponent plays a word using an X later in the game ("Loxodrome"), we know that he must have taken back the X as well. However, that cannot be the case as then "Juxtapose" would not be able to stand without the X. He couldn't play it as part of "Exvin" due to the existence of the word Antothenics underneath Juxtapose.
Suggested correction: I think they were implying that he played a second ex and that's what prompted them to look to see which tiles were missing from the suspects game. Since there were two x's used in the game and there's only X in each set it implies they thought someone was bringing tiles in from another set, and then they looked at the suspect set to see if any tiles were missing.
Continuity mistake: Sam's matchbox, in the interview room, changes from face-forward to back-forward several times.
Dead Ringer - S4-E20
Continuity mistake: When Nick is showing the burger guy the pictures from the ATM, he holds one up while facing the see-through window. He turns and puts it on the table and it's a completely different picture.
Dead Ringer - S4-E20
Audio problem: When Sarah is interrogating the police woman, there are some shots from the left side of the woman when she is speaking and her mouth/jaw movement do not match the words that she is saying.
Dead Ringer - S4-E20
Revealing mistake: At the beginning of the episode, when Grissom notices the body and pulls over, in the close up of him you can see that the steering wheel never moves: he just moves his hand to make it look like he's pulling over.
Other mistake: When the CSIs arrive to take in the accident scene from the Pharoah's Fury rollercoaster, the victims are covered in associated wounds and blood, from such a derailing accident. Yet no brain matter seen anywhere. When in a prior take, two of the rail cars had crashed face down into parked cars and pavement. While two other victims were thrown from railcars while in midair.
