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.
A Bicyclops Built for Two - S2-E13
Revealing mistake: At the end of the wooing near the end, you can see that Fry has four arms.
Revealing mistake: The stunt double's wig in the sword fight at the end is messy and disheveled, yet when it cuts to a close up of Sydney, her hair is silky and flat.
Destiny (2) - S1-E22
Revealing mistake: Throughout the scene where Max interrogates Pierce, the projector changes slides at irregular intervals with no one touching it. (00:22:50)
Revealing mistake: During Kendrix's morphing sequence you can see that the editor did a poor job photoshopping the Ranger helmet and you can still see the white edges of whatever photo they used. It should be tight to the Ranger's helmet and costume like the rest.