Continuity: When the reporters surround Harrison Ford, there are no tapes in the tape recorders.
Great sites
Mistakes
About 35 minutes in, Rusty and Raymond are in the latter's office, drinking White Label scotch. During the scene, Raymond pours himself another drink and replaces the bottle on the desk in a slightly different position. In the next shot, the bottle is back in exactly the same position as it was earlier and before Raymond picked it up. See more...
Presumed Innocent mistakes
Other: When Harrison Ford returns to the crime scene to search for "evidence" we see blood stains on the carpet, which has been on the carpet for days. The blood is bright red and shows no signs of coagulation, but blood turns dark red when it coagulates after only a few hours.
Continuity: At the end of the film when Harrison Ford is working on the fence, it would have been at least a month since the murder took place. But when he discovers the murder weapon, the blood is still fresh and shows no signs of coagulation.