Cross goes through subteranean passages with his gun in his hand, he falls through a hole into water and when he climbs out he pulls his gun out of the holster. he wouldn't have had time to have put it in his holster and is more likely to have dropped it. He dashes through undergrowth to a road and his shirt is dry.
When Alex is talking to Det. John Sampson, Janell is sitting on the right hand side of Vickie while Nana Cross is on the other behind them, but when Alex turns to walk to her Janell is no longer there and he sits down where Janell was only a few seconds before.
While Kate is performing surgery, the earpiece of her protective glasses is seen on the outside of her surgical cap. In the next shot, the earpiece is tucked under the cap.
Kate's hair when she is at the river bank with Alex.
In neither of the sparring scenes, boxing or at the dojo, are any of the sparring partners wearing mouth-guards. No responsible coach or trainer would allow full-contact practice without them.
When the police are following the plastic surgeon in California they are using a 4-door car with California license plate 1E49962. "1E" plates are only issued to trucks or station wagons registered to a company.
In the final scene, Casanova demands Alex Cross shoot him with his Glock service pistol, accurately quoting what was said in James Patterson's book. However, he's mistaken, as the firearm Alex actually uses in the movie is a stainless steel Sig Sauer P226 pistol.
When Naomi is playing the violin, especially the second time, she is often clearly not playing the music being heard, and music continues for a good few seconds after she stops playing.
When Cross is talking to the woman in the hospital, his lips are not moving.
Kate's mouth does not move when she says, "At least now the FBI know who they're looking for."
Naomi's boyfriend mentions that the river in Durham offers good trout fishing. The Eno River (which runs through northern Durham) offers no trout as do no other piedmont NC rivers. To find trout you'd have to go to the NC mountains.
When they are pursuing the plastic surgeon on to Pacific Coast Highway they are shown following him through the McClure Tunnel. The next shot is an overhead shot of them going down the ramp that merges in to PCH from Ocean Ave with the exit of the tunnel to the right.
When Ashley Judd jumps off a cliff into a river she's swept over a waterfall. Recovering in hospital and trying to give clues to the police she doesn't mention the waterfall.
When Henry is talking about Fernando Valenzueala he mentions his knuckleball. Valenzuela was known for his screwball.