Adventures of Captain Marvel

This was the first depiction of a comic book superhero on film.

While a prisoner of the Scorpion, Betty manages to grab a gun and fire a shot that creases the villain's hand. Informed of this, Billy manipulates the expedition's members into showing their hands, and only one man's hand shows an injury. However, subsequent events prove he is not the Scorpion. How the real villain had no injury is never hinted at, and there's precious little said about the wound that was found: After Billy escapes a death trap at the latter man's home, the two have a conversation that is joined in progress, with Batson admitting that he could believe the scientist's story (told completely off-screen) about the cause of his injury if he could explain other things that had happened. Perhaps that trap was originally intended to be a chapter-ending cliffhanger and the explanations were lost in re-editing to eliminate a chapter here.

The Scorpion as Himself

12 Chapters Are Turned Into A One Long Film

Edited into Radar Men from the Moon (1952)