Zombies running over metal wreckage, like the kind that spawn black boxes, get vaporized if they die from running over wreckage. They leave behind no items, not even corpses. Furthermore, loot that spawns in such locations (usually very valuable army gear) is also devoured if it spawns on the metal wreckage.
Vaporization could be considered a bug, but actual vaporization only happens to very low hp creatures, like dragonflies flying over wreckage.
As far as I recall, you can smash corpses stored in wreckages, just not pick stuff up until you shovel it out.
This seems to be happening with the play equipment in a park, such as slides and monkey bars. I killed a zombie child over a slide, and it left no corpse or loot. Smashing the slide didn’t reveal anything.