- After the events of the film, Mandy changed her name, adopted an accent and began to work around the south as a waitress. She also toughen up and learnt about cars.
- It fits everything we're told in the film: The Devil is a decent guy, who hates all those cults worshiping him and doing all sorts of fucked up things in his name. The Accountant seems to think it's virtually impossible to steal the Godkiller. Milton says he just walked in and took it, which could be true because the Devil did nothing to prevent him. The one thing that clashes is why the Devil then sent the Accountant after him? It could be that the Devil has to follow the rules, which say someone has to be sent to hunt down an escapee immediately.
- It could also be that he wants Milton to put an end to the cult, but can't just let him walk free, so he let Milton take the gun and gave him enough of a head start to finish the job before being dragged back to hell.
- God is never mentioned, and when we first see the Godkiller, it is missing one round, meaning that it has already been used at least once. Also, unless it was made to take out members of some non-Christian pantheons, the name implies it only ever had one purpose...
- Milton doesn't really do anything that one might call flirting, let alone anything you might call sex, and yet is irresistible to two supporting female characters, and obviously the best sex the latter has ever had. It's possible that demons/the damned inflame the lust of others, and Milton's high-grade ass kickery might be the result of being wrath incarnate. The copious sugar in coffee might be a quirk of Milton, or it might be a reflection of gluttony.
The order would go like this: In City of Angels, Seth starts out as an angel, invisible to mortals and on God's errand. But during the course of that film, he falls in love with Meg Ryan, who tragically dies. After coming to terms with this tragedy (or not... who knows?) during that film's Gainax Ending, he moves on, settles down again and starts a new life, changing his name to Milton Red Miller.
This leads to Mandy (2018). His idyllic life with the eponymous Mandy shattered by the events of this film, he is forever cracked and broken... nothing like the angel he once was. He lives a broken, tumultuous live, turns to crime and sleeping around, destining himself to Hell.
Thus follows Drive Angry. When his daughter (that he had either by remarrying, or out of wedlock) and son-in-law are killed by a cult and his granddaughter kidnapped, Milton cannot sit idly by and let Hell get away with it. So he steals the Godkiller and drives out of the infernal realm to set things right. Unfortunately, though he does, he also is doomed to still return to his damnation. But it's obvious he will rebel. He's broken out once before, he'll do it again.
So now comes the Ghost Rider Duology. Having been so rambunctious and having caused so many problems, Milton is turned into The Spirit of Justice, allowing the Devil to wield him like a weapon. But when the devil curses Johnny Blaze with the Spirit of Vengeance, the angel Seth/Milton turns the tables and becomes a crusader for justice. The fact that Johnny Blaze starts out as a young man who looks nothing like Nicolas Cage who grows up to look like him is a sign of Translation Convention: the grown up Johnny Blaze probably still looks nothing like our favorite batshit actor, but having us see the angel's visage instead of the mortal he's attached to is a sign that he's the same character.
So when Johnny Blaze recalls that "there was an angel" in Ghost Rider: Spirit of Vengeance, he's hazily recalling Seth/Milton/Red's backstory.