The Return of Wonder Woman - S2-E1
Revealing mistake: During the scenes on the jet with Steve and the others, before landing on Paradise Island and when the Amazon women are aboard, the end of the cabin and cockpit sets are visible at either the right or left side of the screen in some shots (widescreen version).
The Bermuda Triangle Crisis - S2-E4
Revealing mistake: When Wonder Woman drops a mine into the water, she's supposed to be dropping it into the ocean. However, you can see a drain plug of some sort in the background and the "ocean" is obviously a pool, or similar.
Revealing mistake: When Diana is supposed to cut the power cables to stop the timer, just before she cuts the cable, you can see that all the cables are already cut and have a large, obvious seam in each of them. Then, when her hand goes through them, they all cut right at the seams.
The Return of Wonder Woman - S2-E1
Revealing mistake: After the steward releases the gas on the jet everyone passes out, and in the second exterior shot of the jet as it rocks from side to side, we can see the circular frame of the window from which the jet was being filmed, at the bottom right corner of the screen (this shot is flipped).
Revealing mistake: Wonder Woman lifts the rear of the toy maker's van. During the pan from the rear wheel to Wonder Woman you can see the jack holding the van up.
The Man Who Made Volcanoes - S2-E9
Revealing mistake: When Wonder Woman is about to be crushed by the moving wall, one can see the white edge of the set on the left.
Revealing mistake: When the toy aeroplane, which is supposed to be remote-controlled, attacks Wonder Woman, in a closeup shot you can see the wires which are actually controlling it.
Mind Stealers from Outer Space: Part 1 - S2-E10
Revealing mistake: Before the red truck goes over the cliff, skid marks from previous takes are on the road where the police car is.
The Girl from Ilandia - S2-E21
Revealing mistake: After Wonder Woman escapes from the glass tube, she's suddenly replaced by an obvious stunt double who bears little resemblance to her.
The Girl from Ilandia - S2-E21
Revealing mistake: When Wonder Woman tosses balls at Tina for her to stop them mentally, the edge of the protective glass in front of the girl is visible, plus there is a yellowish reflection that wobbles every time the ball hits the glass.
The Girl from Ilandia - S2-E21
Revealing mistake: When Tina and Wonder Woman rate each other's jumps, in the close-ups the background is an obvious blue backdrop that doesn't match the exterior gardens they are at.
The Girl from Ilandia - S2-E21
Revealing mistake: When Tina jumps out of the window, she is a young girl. When she runs away (and all further jumps and stunts in this episode), she is replaced by an adult, taller stunt.
The Man Who Wouldn't Tell - S2-E20
Revealing mistake: When Wonder Woman breaks the door handle in the car, the close-up shot of the second handle she breaks is the previous close-up shot but reversed: she is using her right hand, which swaps to the left hand in the close-up, plus her arm position doesn't match her body's.
The Man Who Wouldn't Tell - S2-E20
Revealing mistake: When the lab is about to explode and the room shakes wildly, none of the stuff moves, revealing the camera trick.
Revealing mistake: Wonder Woman is in a control room with walls and a hard floor, but when she starts jumping around to avoid the lethal red light, the walls and floor swap to wrinkled and bending inwards, revealing it's a room covered with safety mats.
The Murderous Missile - S2-E22
Revealing mistake: The cables holding the missile are very, very obvious.
Revealing mistake: When Wonder Woman tries to stop a car, skid marks from previous takes are already on the road. (00:23:22)
Diana's Disappearing Act - S2-E15
Revealing mistake: Obvious stunt double when Wonder Woman exits through the hole in the wall and when she jumps to face Cagliostro.
Diana's Disappearing Act - S2-E15
Revealing mistake: The black crash mat on the bottom of the crate where Diana falls in disappears when Diana opens the crate.
Revealing mistake: When Bo and Lois Taggert are tossed by Wonder Woman, check the floor and you'll see their shadows bouncing on a rectangular shadow, which is obviously the crash mat.
Answer: The transformation twirling was invented for the 1970s TV series only, to explain her quick change from Diana Prince to Wonder Woman. However, it would have been nice to do a little spin homage in the movie.