Jackie's body was placed on the pyre with her clothes on. When the girls decide to eat her flesh the next morning, her jacket is missing.
The cut on Jackie's arm moves from where she does it on her forearm to closer to her wrist when her body is being prepared for the bonfire. But as Shauna imagined Jackie cutting her own arm, this could easily be an unreliable narrator.
Jackie's body should be completely solid after being dead and frozen for two months but it moves normally when the girls are carrying her.