Revealing mistake: Throughout season 2 on several occasions it's clear that John Terry (Bob Warner) is wearing a fake mustache and a fake beard.
My Journey - S3-E2
Revealing mistake: When Elliot is splashed by the dolphin, if you watch carefully you can see her hair is already wet.
Revealing mistake: There are times when it is quite evident that Michael Rosenbaum is voluntarily bald.
Crossroads - S1-E5
Revealing mistake: When Easy is paddling across the river to aid the British soldiers, there is a shot where the person closest to the camera (Bull Randleman) appears to be rowing, but there is nothing in his hands.
Remy Rides Again/Hassle in the Castle - S5-E10
Revealing mistake: In the episode Hassle In The Castle, in the hall of Infamy the name plates are either scribbles or they're just blank.
Revealing mistake: When Lazare shows up to talk to Will, we see that his left hand has been cut off. When Lazare is about to leave, he has his hands at his sides, and we can see that both arms are the same length, but the left one should be shorter, because it has no hand.
Revealing mistake: In the opening scene when we see Jack and Victor as small boys and then turning into old men, look at Victor when he is a small boy. At one point he looks at the crew. It is over in a split second. Blink and you will miss it.
Episode II - The Samurai Called Jack - S1-E2
Revealing mistake: When Jack cuts the flying car's hood off, he slashes it vertically, but it is cut horizontally.
Revealing mistake: If you look at Les out of Les Alano's' drumming, several time throughout the whole show, you can see he is miming and his stick is not even close to the actual drum.
Revealing mistake: When Shalimar is getting ready to leap on Gabriel, there is a quick glimpse of support wires attached to her.
Revealing mistake: When the school bus is shown cruising around the corner on the way to the camping area, you can see that as it turns the corner is is virtually empty. (01:38:50)
Revealing mistake: At one point when Alan's phone rings (Nokia 8310) he answers it and talks to the caller yet it's obvious he isn't talking to anyone. He blatantly presses the red/cancel button to answer the call. The image hadn't been reversed though, because he pressed the exact same button to end the call.
The Terror - S1-E9
Revealing mistake: When Captain Liberty writes The Terror's phone number on the napkin we can plainly see that she is using a blue bic ballpoint pen - but when we get to see the napkin she had written the number on (again - second napkin) it was written by a felt-tip marker.
The Story of a Divorce - S1-E14
Revealing mistake: In the scene where Reba and Parker kiss outside the restaurant, you can see creases in the scenery backdrop behind Reba.
Revealing mistake: While Archer and the crew discuss the capabilities of The Xindi vortex technology and whether or not to go to Azati Prime, Archer asks Trip to see the data that Trip has collected from the Degra's ship. The camera pans to the display screen, on which a Mac mouse pointer is visible. It is positioned on the line going downward from the red giant.
Revealing mistake: Paul Devildis calls the bank to discuss his restructuring plan. During the shots of the two bankers, on the desk is a notebook-sized, plain brown box. It is very distinctive as it is blank except for a single square white label on the front. Later in the episode Paul delivers his restructuring plan with the bomb inside to the bank. It is in this same box.
Revealing mistake: When Mr. Klimer is chasing Debbie while she says "It smells like poor people", her face is back to normal instead of disfigured.
Christmas Special: Part 2 - S3-E2
Revealing mistake: Many shots show the trees and bushes in full bloom despite the fact it's Christmas. Most notable is the tree outside the pub window in Brent's second date and the bushes outside Brent's window when he's driving around in the daytime. Acknowledged in the DVD commentary.
Revealing mistake: In the scene where the wife comes in to the morgue to view her dead husband, who she helped to euthanize, the dead man is breathing throughout the whole scene. You can see the sheet rising and falling at his stomach. (00:22:15 - 00:24:05)