Continuity: When Alex is traveling forwards in time and drops the photo chain, his fingernails grow a couple of centimeters on his right hand as he grabs it outside the machine's vortex. You don't see him cutting his nails back down, but when he wakes up and rubs his eyes, his fingernails on his right hand have been cut and are clearly longer than the nails on his right hand, indicating that Mara cut them while he was asleep, but not so short to hurt him.
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