Continuity mistake: When Steve and Diana are off the coast of Virginia, they share binoculars to watch for three men coming ashore in a rubber boat, and when Steve raises the binoculars to his eyes the lenses are either extremely cloudy or the lens caps are on (it reflects no light), but in the following shot when Steve lowers the binoculars the lenses are perfectly normal. Then when Steve hands Diana the binoculars the lenses are still normal, but in the following shot when Diana lowers them it's once again extremely cloudy or the lens caps are on.
Visible crew/equipment: After Wotan arrives on the beach Wonder Woman sees the other Nazi with a gun, so when she leaps into the air and lands in front of Steve we can see crew/equipment at the left side of the screen (widescreen version).
Revealing mistake: When one of Wotan's fellow Nazis in the rubber boat starts shooting toward Steve, in the closeup of Wonder Woman deflecting the bullets, one of the wired remotes that control her bracelets' sparks can be seen in her right hand, and as she starts walking toward the camera we can also see the other remote in her left hand.
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.