During the beginning of the game, the main character finds himself in a completely closed-off and isolated area that no one could enter or leave without going through a single door. The player then goes from that area (through said door) to another isolated area containing one body. However, as he is investigating the body, the main character is attacked from behind by a zombie. There's no way the zombie could have shown up behind him as both areas were tightly closed off and isolated.
The imprisoned boy's diary states that the prisoner's planned escape was on October 10th. However, Vincent's diary states in his first entry, on October 10th, that the attempted escape happened the night before.
The goof items below may give away important plot points.
Near the end of the game, the villain character and the Tyrant monster's bodies are left in a hall. However, after the player leaves the hallway we see the Tyrant monster still in the hall, but the villain's body is gone.
Near the end of the game, one of three villain characters is shown being impaled from behind by the Tyrant. However, once the camera pans down to the monster's hand in the villain's body, the hand moves downward as it 'removes' itself from the character's wound, revealing that the monster passed its hand through the character model.