This happens to me on the last lap of almost every race, I get hit by absolutely everything often in a short span of time. For instance in Sweet Sweet Canyon on the final lap, I got hit right before/after entering the launch ramp several times consecutively:
1. Hit by banana right before the boost, causing the boost to be cancelled and making me fall off-track
2. Saved by Lakitu, hit by Green Shell before I regain control, recover right before boost pad, promptly struck by Spiny Shell on its way to whoever is in first place, recover right on the boost pad only to be hit by a Green Shell before I regain control, thus cancelling the boost again and making me fall off-track
3. Saved by Lakitu, successfully boost off ramp only to be hit by Lightning Bolt while in flight, fall off-track
4. Saved by Lakitu, somehow manage to boost off the ramp *and* finally land successfully on the other side