V: The Final Battle: Part 2 (2 Hrs) - S1-E4
Revealing mistake: After the failed raid on the Resistance's headquarters, Brian shoots the counterfeiter who led them there, but no scorch mark appears on his victim's shirt (later victims have these scorch marks).
Revealing mistake: When Donovan escapes from the L.A. mothership with Robin and the Mexican, he once turns the fighter he is using upside down by mistake. But since the passengers have their heads hanging down then, how come Robin's long hair does not?
V: The Final Battle: Part 3 (2 Hrs) - S1-E5
Revealing mistake: During the final battle in the mothership hangar, Donovan shoots a Visitor soldier who falls off his catwalk onto a transporter. When he impacts, a styrofoam block used to cushion his fall bounces off the roof.
V: The Final Battle: Part 2 (2 Hrs) - S1-E4
Revealing mistake: When Julie is almost converted, a fake Donovan bursts in and starts firing a blaster rifle. Look closely at the first shot: the rifle is held way too high, so the shot should have gone into the ceiling; yet the blast goes straight forward.