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).
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 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.
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.
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.
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.