A lot of your cases weren't really fair, because the herculese seems to have died in different sevarities.
I did some more drops
Catapults and Funnelwebs: 2:51
More testing to be done, but it looks like the shield hitbox of funnelweb is used. Detriment behaves very strangely, and there always looks to be a little strangeness when units decouple after death, but it's definitely more pronounced for some units.
it also is strange when a unit passes underground carried by Hercules the intersection point with the ground is behind it.