Revealing mistake: Through out the entire series anytime a body has a gunshot wound you can see that there is no actual hole, just makeup painted dark to look like it.
Dancing with the Fishes - S2-E6
Revealing mistake: While Dr. Hammerback examines the dead cable car driver you can see the "corpse" is still breathing and moving his eyelids.
Revealing mistake: When Messer is trapped in Mr Hudson's safe, the newspaper clippings he pulls out from the drawer show obvious Latin dummy text in the articles, while the headlines are in English.
Revealing mistake: The blond dead victim blinks her eyes when the CSI agents are checking her body. It is right after the CSI says something about her lividity.
Not What It Looks Like - S3-E2
Revealing mistake: When the three thieves destroy the jewelry cases, the case in the middle of the room doesn't shatter. (00:01:15)
Not What It Looks Like - S3-E2
Revealing mistake: After Danny breaks the glass in the lab allegedly using sound waves, you can see in the shot immediately after the glass breaks, a thin green laser beam from roughly further top left to near bottom right. It's assumed this is what actually broke the glass.
Revealing mistake: Season 5, episode 8, "My Name is Mac Taylor": When the killer sets himself on fire, he's not wearing any gloves. In the next shot he is, to protect the stuntman from the flames.
Revealing mistake: At the end of the episode, Jamie Sunderland receives a message from her father to not look back. The closeup on the phone's display shows that the phone is offline and it is visible that the message is in fact a wallpaper.
Revealing mistake: Season 5, episode 18 "Point of No Return": When Danny fires at the bad guy, there are sparks coming from the metal pipes when his bullets hit them. One of the things causing the sparks burns too slowly, taking over a second before it fades out.
Grounds for Deception - S5-E24
Revealing mistake: When Mac shows Stella the photo of The Professor and her "mother", you see that it is the actress (Melina Kanakaredes) with a wig on.
Chosen answer: Probably to broaden the scope of the show's plot and give the audience a chance to see the characters in a different setting, People act differently at home from the way they do at their workplace. By the ninth season, the characters would have become overly familiar and predictable. It gives the writers a chance to do something different with them.
raywest ★