I think some of the time sequences are not realistic... they sometimes pack a lot of stuff into one episode... I think Mack was left with the syringe...
So Mack is safe thanks to John who was the hero yet again but it will not be in his favour when he will be held responsible for all that he has done...
We are watching teenagers in a small village with little escapism... I believe a lot of young people then and now would benefit from what I remember...