It’ll softlock your kart if you aren’t careful
If you haven’t encountered the Mario Kart 8 Deluxe Ninja Hideaway glitch, consider yourself lucky. To everyone else who had it happen to them while their spouse/friend/sibling was laughing at them, as they were unable to actually finish the race: my condolences.
As shown by the Gaming Reinvented YouTube channel below [thanks Nintendo Life], the Ninja Hideaway glitch is actually fairly easy to replicate. Very early on in the track you’ll come across a boost ramp: going off it and landing on the wooden platform above the track will glitch your kart.
This effectively “softlocks” your kart, meaning you will need to eventually lose the race, or quit the game manually to proceed. It differs from a hardlock in that it doesn’t actively brick/crash your game, but it’s annoying nonetheless. Note that this happens more often in higher cc matches, as your speed isn’t always swift enough to carry your kart over the boost ramp and into the glitch spot.
Other YouTubers have been slowly finding more glitches related to Ninja Hideaway, so it seems like a bugged track in general. Keep that in mind if you’re running a local tournament, or want to compete online! Hopefully Nintendo can address it soon enough.