Continuity mistake: After Ash opens the Book of the Dead, he doesn't swaps pages, yet in the second shot the pages the book is open on are different. (00:02:50)
Continuity mistake: Ash's shirt is untucked as he listens to the tape, but when he runs into the room after Linda screams, his shirt is suddenly tucked in. (00:03:15 - 00:05:20)
Continuity mistake: After Ash wakes up by the puddle of muddy water, the amount of mud on his face and neck differs. (00:06:40)
Continuity mistake: When Ash wakes up, after being knocked unconscious by the puddle, he has leaves stuck in his hair. In the next shot they've gone. (00:08:35)
Continuity mistake: When Ash is driving along in his car he has a muddy face, and he wipes some off with a rag, but still leaves a fair amount of dirt on. In the next shot when he gets out the car his face is spotless. (00:10:20)
Continuity mistake: During the first scene where the "evil force" is chasing Ash through the house, you can see above the rafters, showing that this is not actually the house but a set. (00:12:50)
Continuity mistake: Linda's hair is dark as it rolls toward her standing headless corpse, but blonde as it attaches. It's dark again as she bangs Ash's head against the window blockade, but blonde when her head falls off a moment later. (00:17:50 - 00:18:45)
Continuity mistake: When deadite Linda first pops up outside the window in front of Ash her hair is in a bun, but the view changes and her hair is down. (00:18:30)
Continuity mistake: When Linda's head bites Ash's hand, he starts trying to hit it off. He runs to the mantle and hits the head, knocking a green candle off the mantle. In later shots it's back on. (00:18:45 - 00:31:10)
Continuity mistake: When Ash enters the shed to get Linda's head off of his hand, the position of the vice's lever changes between shots. (00:19:35)
Continuity mistake: After the chainsaw was embedded in Linda's neck, we see black blood spray everywhere. After the headless body dies, Ash takes the chainsaw, which is completely clean. (00:20:05)
Continuity mistake: Linda's head in the vise changes from at an angle in shots from behind to straight up in front shots. (00:20:30)
Continuity mistake: There are 5 different colours of blood used throughout the movie. Ash always gets soaked by blood (either chopping Linda's head up, or hacking Professor Noble to pieces), but always ends up dry in the next shot. [The reason why there are 5 types of blood: The creators wanted to get an R rating instead of NC-17, so they used different colors for slime instead of blood. It failed, they got an NC-17 rating and then released it independently with a non-rated rating.] (00:22:00 - 00:45:30)
Continuity mistake: When Ash leaves the workshed after cutting up Linda he only locks the door to the workshed with the chain, later on he goes into it and unlocks the chain and the piece of wood. (00:22:20 - 01:06:20)
Continuity mistake: After Ask looks in the mirror, as his hand starts to turn evil, green slime has appeared on Ash's shirt. (00:22:40)
Continuity mistake: When Ash lays on the floor, after his evil hand has attacked him, the wrappers, boxes, smashed china etc. around him moves around between shots. (00:26:35)
Continuity mistake: Ash chops his hand off at the wrist, yet later it is seen to have a fair amount of forearm attached to it. (00:29:00)
Continuity mistake: The mousetrap is visible outside of the hole in the wall, before the hand gets it's thumb stuck in it and leaves the trap outside the hole. (00:31:25)
Continuity mistake: The hand gets it's thumb caught in a mousetrap, yet in the next shot it's index finger is the one caught in the trap. (00:31:40)
Continuity mistake: No matter how many times Ash has blood poured on him or landed in mud, he will always have a clean face with his freshly made scars, scenes after he has been blood bathed or mud wrestled. (00:34:05)
Answer: Sam Rami could not get the footage of Evil Dead to use in the sequel, so he remade the movie in a shortened form for the beginning. Since Linda was the only original character other than Ash to come back he included her in the recap but deleted the others as not to waste time. An in universe answer could be that trauma of losing his friends made Ash block them out and rewrite history in his head, except for Linda who comes back to haunt him in the movie so he is forced to deal with it.