Factual error: Lots of liberties are taken with the geography of downtown Portland. For example, at one point Bonham is standing on a fountain looking around and, from his point of view, you see two MAX trains on a slope going past a parking lot. Those two points are about a mile apart and there is definitely not line of sight between them because most of downtown Portland is in the way. (01:07:40)
Revealing mistake: When the "light rail" vehicle is crossing the bridge, several shots reveal that it is not traveling on rails, but on a metal grating. This is most obvious after the police have stopped it. We see a bridge deck designed to carry cars & trucks (in fact, the police have just driven out on it) with strips of metal laid on the surface to simulate "rails". As others have observed, this was filmed on the wrong bridge; this makes it particularly obvious.
Continuity mistake: In the car chase scene, when Del Toro gets stuck in traffic, the car behind him stops just a few centimeters before. But when he decides to make room using his car, suddenly the car behind him is a few feet back, providing him with adequate space to drive in reverse (00:57:10)
Continuity mistake: When Bonham follows Hallam down the river he is seen walking on the right bank. In the next shot he is walking on the left bank. (One could assume that he is going back and forth, but that would be very counterproductive on the hunt for someone who is swimming down a fast-flowing river). (01:12:00)
Factual error: After Del Toro jumps into the (Willamette) river he floats/swims to the falls. In fact those falls are about 10 miles upstream from the point he jumps in.
Revealing mistake: In the shot where Jones is caught in a snare and is falling through the air towards the water, he comes to an unnatural stop at the end of his fall. He should have jerked when he came to the end of the rope. Instead, he came to a smooth, controlled stop with no jerking or bouncing. The stunt man was probably lowered with a crane.
Revealing mistake: In the scene where the two "deer" hunters are shooting at Del Toro, the report of the rifles is wrong. The report they use in the movie is for a semi-automatic weapon; you can hear the mechanical clang at the end. These hunters were shooting bolt action rifles.
Revealing mistake: Towards the beginning of the movie, there are several shots of winter wilderness, one with a soaring eagle. If you look closely, you see that this particular eagle has tethers hanging off of its feet. This was not a bird found in nature. This was a trained bird brought in for this shot.