The serial version
Has anyone ever seen the 12-chapter serial of MYSTERIOUS ISLAND? It was a 1951 Columbia flick that took even more liberties than the '61 version from what I've read. The POW's end up on a volcanic island and meet up with aliens from Mercury! Supposedly the serial looks like it cost about $300 and stars Richard Crane.
"We're fighting for this woman's honor, which is more than she ever did."