The goof items below may give away important plot points.
When Eric is hanged and then cut off in his cell, Neville tries to bring him back to consciousness while the cloth strap is still around his neck. However in the next shot, Eric coughs and no strap or even hanging mark can be seen around his neck.
When Eric is hanging in his cell his hands are cuffed behind his back. As the camera pulls out to show Neville fighting the guards, Eric's hands come apart to his sides several times then go back behind his back.