Wonder Woman in Hollywood - S1-E14
Other mistake: When Wonder Woman and Wonder Girl are at Bremer's estate to find Steve and Jim, Wonder Girl's lasso hangs either on the left side of her belt or on the right side, depending on the angle of the shot.
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.