There is something I've always wondered about the franchise in general: exactly what do the Deadites want? I mean, in the first film, it seemed that they were pissed off at being awakened. In part two, one of them says that they desire what they don't have, life. In Army of Darkness, the Deadites are an invading horde. In the few comics I've read, the book itself is an evil overlord and the Deadites are it's subjects. And in the remake, the goal was to give flesh to the Abomination.
It is possible all three are correct. The Deadites are so alien to human thinking it may be impossible to fully understand them. Add on that the book has time travel capabilities. Did Ash awakening them in the present cause them to terrorize the past? Are there different factions of them? One can easily write all three are correct. The Deadites were pissed they were woken up, but once they remembered what life was like they wanted it because they like to terrorize people which you can only do if you are alive.
The Evil Dead
Why was the evil force repelled by the cabin? Except when it wasn't?
The Evil Force could have came in at anytime, it was merely toying with its fresh victims.
Army of Darkness
Bad Ash comes off of Ash's side with the prosthetic hand. In fact he's consistently shown on that side and using that hand throughout his "split" with Ash. When he finally yanks away... he has two flesh-and-blood hands and Ash still has the prosthetic. ... How'd Bad Ash manage that one?
Bad Ash's flesh hand pushed it's way out of Good Ash's shoulder like his head. During the final split he pried his remaining hand out. Since it was really an overgrown mini-ash it had both hands to begin with.
Because they are the humanoid personifications of the evil force that has been tormenting Ash the entire time. Said evil form can take on many forms and has been toying with Ash. Hence why they have both flesh hands, it's a stealth taunt to the fact he has only one hand.
Out of the whole line of prisoners at the start of the movie, why does Sheila single out Ash, who's not even wearing the colors of Henry's men, as the one to blame for her brother's death? I get that it's meant to drive the romantic subplot between them, but it really feels random and forced to me. After all, there's _Henry_ right there for her to vent her anger on, but she chooses our one-handed hero out of everyone...
They are canon of you want them to be. I mean, the movies themselves don't care much about canon.
Evil Dead (2013)
Who was the Deadite who attacked Mia near the beginning of the movie and subjected her to the tree-rape? It can't be the girl who was burned in the prologue, since she was, well... burned, and according to Eric's translation of the Naturom Demonto, that should have killed her.
Word of God says it's the girl from the beginning. Wow, doesn't that open a whole other can of worms...
As mentioned below her father shot her dead before she finished burning, which may have ruined the purification.
It's also possible that what she saw wasn't the girl from the beginning, Word Of God aside, but was instead a demonic version of Mia, which was the image her mind projected onto the Force. This at least would jive with the fact that the image Mia sees is a brunette girl wearing a white dress, such as Mia wears when she really starts acting possessed (the shower scene and thereafter), whereas the girl in the opening was blonde and wearing a vaguely purple-ish dress. This also fits with what Olivia sees just before she gets possessed, namely a hissing, feral reflection with the Glasgow Grin she will shortly be sporting. It may be that whenever a human sees the Force, their mind projects a warped version of themselves onto it.
In the commentary, director Fede Alvarez refers to the girl as "Evil Mia."
How is it that the necklace that Mia breaks at the beginning of the film is perfectly fine after the house is destroyed? There is no possible way that David had enough time to fix it in the short time between the conversions and the house being destroyed.
How was it that Mia was able to keep the chainsaw running even though the gas cap clearly fell down the hole? There was no way the chainsaw could have kept running when the was maneuvering herself under the car without the cap.
Same reason how Ash can shoot three times a two-barelled shotgun. Being the designated survivor in an Evil Dead film at least has some perks, infinite ammo being one of them.
A math problem: The Abomination needs five souls to rise. It never seems to get more than four over the course of the movie. How do the numbers add up?
Possibly Mia doesn't get her soul back, even though she's freed from possession.
In the original ending, Mia was still possessed, but still, only TWO souls (Eric's and Olivia's) were harvested, three if we count Grandpa the dog.
Could be Fridge Brillance: the dog?
Mia died for a moment, so the Abomination clearly didn't need five souls, just five deaths as a sacrifice.
No, no. They clearly state five SOULS, so that's not it.
Possibly, every person who dies while the Evil is active counts as a "soul" toward the Abomination. So there was the girl in the beginning, her mother that she killed, then Eric, Olivia and Natalie. The Evil was inactive between those two incidents, but not defeated, so it could have "saved" the girl and her mother's soul toward the Abomination.
That's an explanation, but it sounds way too much like grasping at straws. What was wrong with something like 'Five must die'? If in a possession movie you use the word 'souls', you usually have to mean 'souls' and explain yourself if you don't. But of course, seeing some scenes like Eric reading the book, it comes off quite clearly that They Just Didn't Care.
It's possible that the Abomination needed Mia's soul to rise, but when her soul is returned it leaves it weaker. The Abomination seemed like barely more of a threat than the deadites, and indeed seemed worse in some respects.
Another explanation is this: you don't actually have to die while possessed and without being purified; you just have to be possessed in the first place (heck, Eric is possessed after he dies). In this case, a temporary possession still counts, which would mean that the five souls are the girl from the beginning, Mia, Olivia, Natalie and Eric.
According to Word of God, the 'Abomination' which looks waaay too much like Kayako from Ju On is actually the girl from the first scene. How this could happen since she was CLEANSED is anybody's guess, and I think we can rule out the 'Evil took her form' since they said it was the girl, and not the Evil taking her form.
In the beginning the father shot his daughter dead before she finished dying from the immolation, so it may not have fully purified her as it should have.
Also worth noting is that the end credits list that creature as "Abomination Mia", so some of the "Word of God" stuff on this page may come from faulty sources.
Both Natalie and Mia being able to cut off an arm very easily. BONES. DO. NOT. WORK. THAT. WAY.
With Mia, a jeep fell on top of her arm. This could have easily broken the bone, meaning that the only things holding her in place was her skin and muscle; which could also have been damaged by the jeep falling on her arm. With Natalie, the electric knife actually shorts out once she reaches the bone, meaning she may have found another way to break it in the time it took the guys to find her.
She did find away. While it was offscreen, Natalie is later seen leaning against the fridge moments before her arm falls off. There was a lot of blood staining the fridge above and below the wound. She could have smacked her cut arm off of it till it broke.
Why is Ash not in a mental institution, serving a life sentence, or dead after killing nearly a dozen people? Certainly he would be arrested for that and I can not imagine a feasible defense for him outside of insanity.
Evil Dead 2 retconned Cheryl, Scotty, and Shelly out of existence, and made it so Ash actually didn't rent a cabin (the cheapo broke into the Professor's place!) so there is probably no one who knows he was there. Whenever the authorities end up investigating the scene.... well, it would be quite a mess. The cabin was partially smashed by those tress, and the portal most likely sucked a lot of evidence of what happened there.
It didn't retcon them out of existence - Sam Raimi has repeatedly said that if you cut off the beginning of Evil Dead 2 and put Evil Dead 1 there then did the same with Army of Darkness its the whole story as he envisioned it. So the incident still clearly occurred. However your second point is very likely the exact reason why. The portal very likely swallowed up anything that anyone would recognize as human remains before it closed, if much of anything remains of the cabin after all that's happened there.