Revealing mistake: When Nicole's bike jumps over the kids lying on the ground there's a ramp beside them disguised as part of the road to allow for the stunt.
Revealing mistake: When Nicole Kidman shows the kids some tricks she is replaced by a very obvious stunt, older, taller and... a man. Confirmed by Nicole Kidman, who said her stunt double was "a teenage boy wearing a padded bra." Source https://www.smh.com.au/culture/celebrity/kidman-s-made-off-like-a-bandit-in-hollywood-all-without-the-bmx-20211216-p59i2t.html. (00:36:58)
Revealing mistake: When the red and blue biker are on top of the van, before it crashes they're replaced with very obvious dummies.
Revealing mistake: There's a short ramp by a truck's cargo bed, but when the bikers ride over it, it's become a longer ramp that goes up to the cabin to allow for the stunt. (00:06:14)