At 00:18 -Zari sets her timer to 23:45 in order to warn the team when their immortality spells are about to run out. She allows for a 15 minute buffer. But at 36:34 both the timer and the spell have run out -ignoring her 15 minute buffer.
Although supposedly in England, the bus was driving on the wrong side of the road, was left-hand drive, had passenger doors on the wrong side, and the Legends were waiting for the bus on the wrong side of the road.
Since Nate is invulnerable in his steel form, he shouldn't be threatened or killed by the zombie horde. Earlier in the episode, they show that a zombie is unable to harm Nate while he's in his steel form.
When the Legends are picked up by the Army, Rory, who is supposed to be from the USA, exclaims in a very Australian accent that he has been in one of the prisoner transport vans before.