Continuity mistake: After Brenda hears a noise, she puts her book down next to the candle, and walks to the door. When she gets to the door, the book is now by the opposite side of the candle. (00:52:50)
Continuity mistake: After the sheriff gets the call over his radio, he turns on his red lights. In the next shot they are off again, and are then turned on once again. (01:00:25)
Continuity mistake: When Alice wakes up she has white socks on. When she walks to the kitchen they are black. (01:08:00)
Continuity mistake: After Brenda is thrown through the window, she is facing to her right. Later when Alice goes back to the kitchen, she is facing to her left. The glass and wood around her changes too. (01:11:20 - 01:20:15)
Continuity mistake: When Alice runs into the barn to hide from Pam, as she slides the door open, a plank of wood falls over, to the right of the door. In another shot of the barn, it is upright again. (01:17:00)
Continuity mistake: After Alice bangs at the lock with the end of the gun, the position of the lock and it's chains differs through the following consecutive shots. (01:17:50)
Continuity mistake: After Alice hits Mrs. Voorhees with a frying pan, Mrs. Voorhees's arm goes from being by her head, to laying across her stomach. (01:22:30)
Continuity mistake: When Alice runs to the beach, there is only one canoe sitting there. But when she finally gets in the canoe and pushes off, there are two. (01:23:10 - 01:25:15)
Continuity mistake: Alice knocks the machete out of Mrs. Voorhees' hand, and we see it land. But when Alice runs and picks it up, it is in an entirely different place. (01:23:40)
Continuity mistake: Just one shot before Mrs. Voorhees's decapitation, you can for a split second tell Alice's hands are empty as she swings, and that she's not really holding the machete. (01:24:35)
Continuity mistake: In the scene when Alice decapitates Mrs. Voorhees and Mrs. Voorhees raises her hands and grabs air, if you look carefully, the hands have hair on the back, even when, during the chase scenes, she doesn't have hair on the back of her hands. (01:27:55)
Continuity mistake: When Ned fakes drowning he is a decent distance from the dock. When he is rescued he is much closer.
Continuity mistake: Crazy Ralph comes out of the pantry and Alice screams. Marcy and Ned come running into the kitchen. Ned is eating a hamburger that hasn't been cooked until the next scene.
Answer: 1. She was most likely hanged. 2. Mrs. Voorhees wasn't possessed by Jason. She simply went insane when Jason drowned and wanted revenge. 3. He's not burnt, only disfigured.