Revealing mistake: In the nursing home when Budlofski and Matheson are looking for Saul, we see Saul break a coffee pot over Matheson's head. When the coffee pot breaks you see coffee splash across the top of the camera.
Revealing mistake: While Punisher is killing Pittsy, you can tell he is holding a dummy, not the real girl.
Revealing mistake: At the beginning of Angela's bathroom death scene she is looking at herself in the mirror. You not only see her reflection in the mirror, but also in the shiny metal strip holding the mirror at the bottom which is to be expected. When she turns away and her 'demon' reflection is watching her, you still see the image in the metal strip. As the 'demon' is in the mirror you should no longer see anything reflected in the metal. This does seem to show how these moments were filmed, with the real actors reflections being recorded.
Revealing mistake: After Trevor has been lowered above the pit of magma, in an attempt to light the magnesium walls with a flare, we see shots of Sean hanging over the edge of the inside of the T-Rex skull. Sean's hands are resting on a large tooth in the skull, which clearly shakes like a fake prop each time he touches it. (01:17:15)
Revealing mistake: At the end of the movie Melissa jumps from the burning truck leaving Rusty inside. As the truck bounces down the slope it catches on fire and explodes. You can see the engine compartment of the truck is empty, no radiator or engine, just an empty volume illuminated by the flames. (01:24:00)
Revealing mistake: In the explosion of the opening scene it is apparent that cut scenes have been shot with several hours time difference because the sun has moved. This is best visible in the reflection of sun in the helmet and shadows of the vehicles in the background.
Revealing mistake: As Rob, Hud, and Lily are rescuing Beth from her apartment, the view outside the window is tilted roughly 45°. This is due to Beth's apartment building being partially collapsed against another building, demonstrated previously by an exterior shot. However, the characters are moving within the apartment with no difficulty or apparent change in gravity, even though they should be struggling to remain upright in a significantly tilted apartment. This makes it clear that the scene outside has been added using chroma key technology, and the camera has simply been tilted to create the illusion that they are on an angle. (01:01:30 - 01:01:52)