It's Always Sunny in Philadelphia (2005) - 10 mistakes in entire show

Continuity: While Mac is holding the picture of himself to Dennis & Dee, towards the end of the scene he is holding the picture with one finger around the middle on the top edge. Dennis then says "You're going to hell". The next shot he is holding the picture by its side with two fingers.

Revealing: During the scene where Dennis and the Waitress, Mac and Dee successively walk into the back office to talk to Charlie near the beginning of the episode, in some of the shots, you can see outside the office door, and you can see the top of the set has no ceiling, and even see part of a stage-light.

Continuity: When we see Mac and Dennis smash the boards successively over Charlie's back, as the camera cuts to a closeup of Charlie, Dennis suddenly appears behind him, despite the fact he already smashed his board and walked off-camera.

Continuity: In the opening scene, as the gang is being mugged, watch the background. Towards the end of the scene, there are suddenly three cars parked on the street behind the gangs after a brief cut to the mugger, despite there having been no time for them to all appear.

Revealing: During the training montage, right as Mac is about to smash the bottle over Charlie's head, you can see Charlie stop what he's doing about a half-second before being hit, and brace himself for the impact, despite not being able to see it coming. This is confirmed on the DVD commentary.

Audio problem: When the Vietnamese man is playing Russian Roulette in the end, a few seconds after picking up the gun, he moves his thumb and we hear the gun cock. However, you can see that he didn't actually cock the gun, as his thumb never came into contact with the hammer while moving, hence the sound was a phantom sound.

Continuity: When Mac and Dennis are talking to Doyle on the bus, watch the background outside of the window. Every time the camera cuts back and forth, the background changes. The most noticeable change is near the end of the scene, when the background changes from trees and shops passing, to suddenly the side of a bridge passing.

Revealing: When Liam is stabbed in the arm, as he turns around to walk away, you can see the outline of his real arm wrapped behind his back, under his robe for about one full second, revealing that the arm he was stabbed in was a fake prop-arm.

Continuity: Early in the episode, it is mentioned that the serial killer is murdering "Young, attractive blondes", yet at the end of the episode, when the gang finds all the severed heads in the killer's refrigerator, almost none of them are blonde or young, contradicting what had been previously established.

Factual error: Charlie drops the moltov cocktail into the police car in the end, light enough so that it doesn't break, but the car explodes about ten seconds later, as Charlie explains he had soaked the entire inside with gasoline. However, there realistically wouldn't be such a long pause as shown in the show for the gasoline fumes to ignite. Also, the explosion is much more powerful than it realistically would have been, revealing pyrotechnics were used. Obviously done for comedic value, but still a mistake.