Revealing mistake: In the shot where Jack and Harry are descending a ladder to the stranded elevator, we get a good look at the elevator shaft and its surroundings. Upon closer inspection you'll notice how the lowermost section of the shaft is actually a mural - given away by the shadows cast upon it. (00:09:20)
Revealing mistake: When Traven is walking back to his car before the first bus explodes, as the bus drives past him, you can see from the shadow it casts that the bus isn't driving straight on. It turns the corner behind his car. Obviously a prop bus is further down the street and that is the one that blows up in its place.