So, I've seen many theories on why the rift is here, and why the zombies are there.
So, I wanna tell you guys why the rift was created, and why the zombies are there... If it's anything the Doctor Who hasn't told me.
In a Episode of Doctor Who, Rose Tylor went to visit her Dad in the past (Stay with me here!). But she asked to see the point where he Died.
Rose never met her dad, and for some bizarre reason this is the point she wanted to see her dad... ok.
Anyway, she watched him get ran over by a car, and he watched him die. She then said, let me see it again Doctor. So she hides out of sight and waits for her Dad to cross the road. (You following?)
When he started to cross the road, Rose jumped out and got her Dad out of the say of the moving car, letting him live.
(When shit hit the fan)
So now the rift is broken, because something that happened in time has been changed.
The Doctor can no longer use his time machine and they are trapped there.
Now, the car that was going to run over her Dad keeps on appearing and disappearing in the same spot each time, going round and round on a loop (you following?) and it doesn't stop.
Because the rift is broken, these creatures with red eyes appear, as they are there to fix the rift. They basically want to kill Rose Tylers Dad, because with him alive, shit is going down.
You know that these creatures are controlled by Satan as everyone has to run into the Church for safety, and because of this the creatures can not attack them.
Near the end of the episode, Rose's Dad runs out of the church and in front of the on-going loop of the car. He Dies in that spot. The creatures then disappear and they and the car keeps on driving.
Now, that may have mind-freaked you guys. But I will just say the basics.
1. Rose broke history.
2. Rift broke.
3. Creatures with red eyes come to fix it.
4. The car that was supposed to kill Rose's Dad, kept going on a loop.
5. The creatures were Satanic, and did not attack the church.
6. Rose's Dad jumped in-front of the car.
7. Shit got fixed.
^ That my friends is basically the exact same stuff that is happened on MOTD.
1. The 4 men re-wrote history because they killed the guard. Letting all 4 prisoners escape.
2. Rift broke.
3. Creatures with red eyes appeared in the prison to fix the problem.
4. The 4 men are now stuck in a loop until they fix the problem.
5. The creatures are Satanic, as we can see with many, many clues around the map.
6. 3 Members of the crew died, Al escaped.
7. History was re-written HOWEVER, the final out-come of the 3 men dying of electric chair still happened. So then stuff got fixed.
How the story ends, is what matters.
Dr Who always says, time can be re-written. It's just the outcome that needs to stay the same. The story said that the 3 men, died of electric chair on New years eve. Which they did. However, since the rift was broke when they arrived dead on the bridge, History was the same, but then they could revive themselves. Then the 3 men still needed to die, however, Al could escape as that was only 1 little part of the story that he died, and that could be re-written, and it was.
So when Al and the Zombies (remember, they want to fix the rift. And at this point, killing the 3 men is the only way to do that, so they go for them and leave Al alone) kill the 3 men, the cycle is stopped, the rift is fixed and time keeps going.
Now, if you need me to explain that ^ lump of mess, I can. Just ask me!
But I hope this helps you guys!