Towards the end of episode 13 we get too see a close-up of Phil's left hand. Even though he has been hospitalized in a full coma for several years, he has a suspicious amount of dirt under his fingernails. In reality a coma patient would hardly have the chance to get his fingernails dirty.
At the very beginning of episode 15 Sasha reaches out to close the open eyes of his dead friend Bee. Bee, however, closes his eyes a fraction of a second before Sasha actually touches his face.
Even though episode no.7 is set in 1993, a big emblem referring to the 850th anniversary of Moscow is clearly visible. The 850th anniversary of Moscow, however, was celebrated in 1997.