The big surprise is that the USN had a functioning torpedo in 1942. From what I’ve read, virtually NO US torpedoes worked at all until spring-summer 1943. Ironic that this early one took so many US lives; although once in Japanese custody, their survival outlook was pretty grim anyway, torpedo or not.
Depended on how the torpedo struck If hit at oblique angle would explode - it struck dead on (90 deg) the firing pin would jam Also if magnetic exploder would often malfunction and explode prematurely