When Chris and Dani are at the police station and about to have sex, her shirt mysteriously reappears. They are kissing and Chris is shown removing her shirt (leaving her in a red bra). A few seconds later they are still kissing, and you can see that her shirt is back on.
The Rock "nips up" when he is wrecking the casino. This is a kind of trademark from his days as a WWE wrestler and has done it in every movie he starred in.