Actually, both situations probably involved a unit employing a little-known piece of German equipment called the "Dratipizzedmishortzenwaffe." First deployed in the summer of 1944, it was intended as a last-ditch defensive device if troops were being overrun. Essentially, it was a set of boxer shorts impregnated with an incendiary explosive that lacked only one ingredient: urea. Casualty analysis by the Germans showed that troops in the midst of being overrun would, obviously, have their hands full doing other things (shooting, reloading, etc.). Because of that, they were unable to draw a weapon at the last second in order to at least take their attacker with them and, the high command would hope, blunt the attack. Therefore, the Germans began to develop weapons that did not require the use of the hands. Some were immediate failures, such as the panzeroffnung (a.k.a. mouthzooka), while others (including the dratipizzedmishortzenwaffe) showed promise and saw limited deployment.
The dratipizzedmishortzenwaffe was at first beloved by the troops, especially on the east front. This is because the other ingredients of the explosive made the dratipizzedmishortzenwaffe take the form of a pair of warm, quilted boxer shorts. In order to facilitate the transmission of urea into the dratipizzedmishortzenwaffe, the interior was even lined with some of the depleting stocks of flannel! The love affair soon ended, as in a shocking oversight, the Germans had apparently forgotten that there were many, many things on the battlefield which could cause the user to initiate an accidental deployment of the dratipizzedmishortzenwaffe. Some historians suggest that the oversight was known, but simply ignored because of the increasing desperation of the strategic situation. The lucky users experienced a form of misfire that merely made them seem extremely flatulent. Soon after deployment, several counteroffensives stalled in a frenzy of exploding pants, and the dratipizzedmishortzenwaffe was quickly withdrawn from service.
That was not the end of the dratipizzedmishortzenwaffe, as the Allied forces found abandoned crates of the devices as they moved deeper into German territory. The "liberation" and deployment of the cozy, but deadly, undergarments is an understandable mistake, and likely explains the end of your mortar crew. It sounds to me like some incoming fire came uncomfortably close to your crew (wearing captured dratipizzedmishortzenwaffe), and that obviously triggered an accidental deployment.
Kudos to Big Time for the incredible level of detail and obscure historical research that led to the inclusion of this hated but innovative device!
Brad "Supertanker" Wohlenberg