If you study a Bergen County, NJ map, you would notice that Route 4 does not have any major connecting highway to the tunnels to New York. Route 4 was flashed briefly has he exited to Saddle River Road. The quarry is on the Southnound side of I-287, near Wayne, NJ. Mel's character uses Route 4, which only leads to the George Washington Bridge.
After Tom has raised the reward to $4 million, there's an angry telephone conversation between Tom and Shaker. You can see Shaker's lips still move for a split second after the audio of him saying "Look at your wife" has stopped.
In the final scene when Tom takes Shaker to the bank Shaker has his arm in a sling and not in the arm of his coat but after he shoots the cop and he and Tom fight, his arm is no longer in a sling and is in the arm of his jacket.
After shooting Maris and the 2 hoods, Shaker reenters the apartment, leans next to Sean in bed, and speaks to arriving Police Officers in a way Sean would have heard him. Later when Shaker is at the apartment getting a check written, Sean is so frightened that he pees when he appears for the first time to hear Shaker's voice.
When Sean spits the cough syrup on Maris' shirt you can clearly see two large red spill spots on the left and right side. In the next scene she comes into the kitchen wiping her left side while the right side is completely clean.
Towards the end of the movie, Sean is lying on the bed wearing only one sock on his right foot, seconds later he is wearing both socks, seconds later again he is wearing only one sock but it is now his left foot that is bare.
When Tom returns in his penthouse after the failed transfer of the ransom money, he hugs his wife. In 2 shots (alternated with Hawkins talking) Tom has his left AND right arm on his wife's back. The next shot (when you hear the other FBI-agent say "this is no high-tech mastermind") Tom has his left arm UNDER his wife's scarf. Next shot Tom's left arm is on the outside again.
While Mel Gibson's character was driving to the quarry, notice that the same store fronts keep passing by. The most obvious one would be the yellow sign or a few lights that keeping repeating. This was because they were just driving up and down one section of Route 4 in NJ.
During the car trip to make the payment Jimmy speaks to Tom about "The time machine" and the two species: Morlocks and Eloi. At a time he states that Morlocks eat the Eloi, so they are cannibals. To be considered cannibalism a member of an species has to eat other member of the same species. So a Morlock eating Elois is not considered cannibalism. Could be considered a mistake of the character, who could not know this.
Tom leaves the trunk of his Jaguar open when going to the news van to take their keys, and when walking back to the Jaguar the trunk is closed; however, when the shot begins after leaving the van, the jack handle is no longer in his hand, and he is next to the car door, so it can be assumed that he's put the jack handle back in the trunk & closed it before getting to the car door.
Clark starts the van and drives it at Shaker. Shaker shoots him but in the close-up showing the bullet hits, the van is stationary and in the same place it was parked. In the next shot, the van is moving again.
In the check writing scene, the trigger on the Glock is in the "fired but not reset" position. If this gun is not fired the trigger is in the "full forward" position. If the trigger is pulled but the gun is not loaded, (so the slide does not cycle to reset the trigger) the trigger moves to a position where it is much further back in the trigger guard.