Due to The Golden Turkey Awards, where most people first heard of Ed Wood, many believe that at one point that Dr. Vornoff declares that Lobo is a "gentle as a kitchen", when he clearly does say "gentle as a kitten"
Many recall Bela Lugosi bellowing his "race of atomic supermen" speech at the top of his voice, likely due to Martin Landau playing the scene that way in Ed Wood. While Lugosi is quite the Large Ham in the actual scene, he's nowhere near as over-the-top as is often remembered.
Executive Meddling: Donald E. McCoy, who financed the film and served as executive producer, insisted on the anti-nuclear message that is featured in the film. Some claim that he also insisted on his son Tony being the leading man, though others have said that Tony had already been cast, and introduced Wood to his father when Loretta King proved unable to finance the film.
Name's the Same: The guy who did the sound effects is named Mike Pollock. No, not that Mike Pollock.
The Other Marty: Loretta King replaced Ed Wood's girlfriend Dolores Fuller, because Wood believed King when she said she could finance the rest of the film. Fuller was given a minor role, and the one instance in the film in which the two actresses interact is... strained, at best. Give Fuller credit for keeping her cool and being a professional about the whole thing.
That's Dolores Fuller's version. Loretta King's is that Wood hired her flat out after seeing her in a play, and that Fuller was much less professional about the whole thing... (Of course, King's word is less than believable when considering she wasn't honest about other things - like being able to back the film.)
An even weirder one: Dr. Vornoff was going to be played by... Boris Karloff. Lugosi really wanted to play Vornoff, but was told Karloff got the job and he'd be cast in a - yep, you guessed it - vampire movie. Wood was going to use Lugosi for the film The Vampire's Tomb. When Lugosi found out he would be cast as Vornoff after all, he was pleased.
Parody Retcon: The film has a generally less serious atmosphere (and dialogue, in particular) than most of Wood's other output. This has led to suspicions that Wood's co-writer, Alex Gordon, originally wrote the film as a parody of mad science flicks, but Wood directed it as if the plot were being played straight.
Reality Subtext: The film Ed Wood underlines it, but many people have noted that Lugosi's rise and fall in Hollywood made his speech about proving he's as good as he ever was hits home, since it was one of his last speaking scenes in his career.