Older Than They Think: The idea of Red Skull's facial deformities being caused not by exposure to Dust of Death but a flawed version of the serum later used on the Captain, which was later adopted by Captain America: The First Avenger and some of the animated adaptations, actually originated in this film.
And his mask appears poorly fitted to his face, particularly in the film's closing shot.
The mutated rat near the beginning reeks of terrible stop-motion.
Tear Jerker: Bernice's death. Sharon doesn't take it well.
WTH, Costuming Department?: The obviously fake ears on Captain America's costume, put there because the mask originally went around Matt Salinger's ears, but caused some rather painful chafing, necessitating the fake ears.