Revealing mistake: When Terrible Tommy has Rosa in an airplane spin her hair suddenly gets thicker and her legs get thicker, indicating this is Rosa's stunt double.
Below the Belt (1980)
1 revealing mistake - chronological order
Directed by: Robert Fowler
Starring: James Gammon, John C. Becher, Mildred Burke, Regina Baff
Other mistake: When Tommy tries splashing Rosa during their match she hits the ring mat with her chest and stomach yet seconds later she's somehow knocked out. I never saw her head hit after multiple viewings of that scene.
Trivia: Director Rob Fowler reportedly wanted Raquel Welch as Rosa Rubinsky since he liked One Million Years B.C. But the studio insisted on the lesser known Regina Baff.