Revealing mistake: After Rygel realizes that he can loosen the soil with the dumped gruel, it cuts to John and Aeryn as they approach the Tavlek camp, and when Aeryn tells John, "I am going to take out every last Tavlek. No survivors. No mercy. Now give me the oculars," John holds up the syringe (with Zhaan's sleep mist) that Aeryn had given him earlier, and we can see "DG-4" engraved on the side of the gun, revealing that the prop dept used the model DG-4 aluminum air blow dust gun to play the part of the syringe.
Revealing mistake: (Part 4) After Omega takes off his mask and looks in the mirror, when he sees that his physical body doesn't exist he puts his mask back on and screams, but when he shouts, "If I exist only by my will, then my will is to destroy," Omega's mask pops up off his face, and we can see the actor's blackened face as he shouts the last bit of his dialogue. (00:07:10)
Revealing mistake: When KITT takes part in the race and goes up on two wheels, you can see that the stunt driver is behind the wheel and that a dummy is strapped into the passenger's seat.
Revealing mistake: When they show the soldiers killed by the Dalek, in both the hallway outside the cage and the large room in weapons testing, they show some casings which were ejected from the soldiers' guns. The casings still have projectiles in them. If used, they would have been in magazines and would never fall out like they are shown.