With modern torpedoes, this is a lot less likely to happen. The wire-guided ones you can command to go back the right way. The non-wire-guided surface-launched ones can be programmed so that if they get turned around too much, they auto destruct.
Just for those who may not know: this is historical. Tang was shot by her own torpedo when it hit the surface and made a full circle, killing nearly everyone on board.
American torpedoes were tested poorly in ideal conditions without their proper weight in them. And then had parts substituted because they were cheaper, easier to obtain, or quicker to manufacture. This lead not only to the torpedoes running incorrectly due to their weight being wrong for the guidance system, but also for some to have their detonators fail to detonate because the metal in the mechanism was made of a soft metal that bent or squished when impacted, resulting in the detonation pin not striking the charge.
Once these problems were identified and corrections made (sometimes to existing torpedoes) including some additional stabilizers to the fins, the American torpedoes became not only accurate, but quite deadly. As several Japanese vessels discovered starting in 1944. Several, meaning "A lot of them".
This lead not only to the torpedoes running incorrectly due to their weight being wrong for the guidance system, but also for some to have their detonators fail to detonate because the metal in the mechanism was made of a soft metal that bent or squished when impacted, resulting in the detonation pin not striking the charge.
And those were magnetic detonators, not contact. The torpedo was supposed to pass underneath the keel, not hit the sides of a ship, except that was what happened because of the aforementioned guidance problems. And once the depth problems were fixed, the detonator didn't go off because it was calibrated for the magnetic field in Newport, Rhode Island. That was fine for the North Atlantic, but most torpedoes were headed for the Pacific.
Oh, and BuOrd blamed the problems on "user error", making it harder to get the torpedoes fixed, because there was no possible way the problem was in the torpedo's design or the minimal testing they did (NTS Newport couldn't even fire a live torp on an obsolete ship, because they would have to pay the costs to salvage the ship if it sank).
