Many times throughout the movie, Logan gets his weapon knocked out of reach, but is then holding it moments later when there was no time to retrieve it.
The ugly Oldsmobile on the LA freeway is missing its right front hub cap, but is has been replaced by the time the car pulls into the parking lot.
When Tess, Russell and Patrick are sliding down the water tube, there is a very heavy quantity of water gliding them down. When they finally reach the end and land on the platform, there's barely a trickle of water coming out.
Logan's shoes as he climbs through the church window.
When Patrick jumps out of the acid bath, he's completely covered in flames. A mere seconds later, the flames are all out.
Russell and Patrick both slide down the water tube in the final battle and become soaked, yet Russell has no problems lighting his Zippo lighter - Zippo's are not waterproof.
Obvious stunt double when Patrick Channing breaks through gas chamber glass.
Obvious stunt double for Patrick Channing when Tess knocks him off the platform with a metal bar.
After Channing is knocked off of the platform by Tess, Logan is hanging onto the bottom rail and a black rope and safety cuff are clearly visible.
When Channing jumps off the building, the safety rope attached to the actor is clearly visible.
Set in Los Angeles, yet Chicago's Sears Tower is visible in the background.