Note that there was no wumpa, however, it could've been the exact spot where it would normally be.
Yes that happens. If you throw something like a nitro or a TNT in the exact spot where there's a wumpa, it will immediately explode. I used to do this mistake a lot in Slide Coliseum as a child playing casually. That's why you use as less items as possible during a speedrun imo.
I haven't seen that before but it looks as though you get a really late jump off the pillar. You can do a jump with all 4 wheels off the track in some places which gives you extra distance.
Best thing to do off the pillar is drift, even if you don't go for the second shortcut, it'll still give you a tighter racing line.
Oh...initially I thought it happened because the game thought I tried to jump off the edge of the track beneath...but anywho, that random jump ruined my setup for the shortcut :P
And drift you say? I always felt it would end up in me falling so I just thought aim for the right, hop and aim to the shortcut. (Was trying out the Papu skip, still trying to learn! Zero successful attempts so far).