Revealing mistake: The Apocalypse/Mayhem: When fighting Straga, he reaches down into the pit of lava he's standing in and throws cars at you that he pulls from there. Only these cars he pulls out of the lava look perfectly fine, with tires, paint, windows and everything still in tact despite being submerged in molten rock.
Revealing mistake: The Apocalypse/Mayhem: During the cut scene before your first battle with Straga, various Angels and Demons are fighting. It shows one Minion Demon holding an Angel Soldier, and in the over head shot he's holding the Angel's torso up off the ground. When it cuts to a side angle just before the Demon rips out the Angel's throat, suddenly the Angel is not only on the ground, but almost completely inside the ground with just part of his face and torso sticking out in a bad animation moment.
Revealing mistake: The Apocalypse/Mayhem: During this level, meteors are constantly falling down to the earth. A lot of items in the environment are destructible, including all vehicles seen. However, if a meteor strikes a vehicle, like a bus, it does nothing to it. But rather passes right through the bus and just leaves an impact crater under it.
Revealing mistake: The Choking Grounds: After defeating the four arena challenges in the Realm of Shadows, and going back to Gatekeeper and summon him up to free him. There is a tree to his left, on War's right, that has low hanging branches and a lantern hanging from one branch. As the Gatekeeper is standing up, his left arm passes through the branch and lantern. This is a being made of solid rock and the tree and lantern phase through it's arm like a ghost. His right arm also passes through some of the leaves on the right side of him.
Revealing mistake: Scalding Gallows: There is lava all around Samael's prison down in a chasm. Jumping down into it triggers the lava death animation with fire all around War. However if you jump towards the secret chest and miss, landing on the stone face of the wall you still die. Even though you don't actually touch the lava yet, it still triggers the lava death animation.