When Kit tells the chief about the simulation that was done in 1994, both actors said "1993", when the scene was filmed, but "1994" was dubbed in later. In a later scene, when Kit refers to the simulation again, she says "1994".
After Kit and Madelyne stop the water gushing in and escape the tanker rolling on top of them. George comes from the other side of the tunnel shouting that they've started digging. He then starts to scream like a girl before the vehicle lifts up and swallows George into the hole. Was he screaming like a girl to get his point about them starting to dig or did he miss time the vehicle swallowing him.
When the explosion reaches the mouth of the tunnel, the cars entering stop in straight lines. After Kit and his passengers get out of their car, completely different vehicles are scattered everywhere, and some have overturned.
When Kit tries to go toward the Mid-River tunnel to bring Roy back out, Kadeem grabs him from behind, wrapping his left arm around Kit's neck. George grabs Kadeem from behind and Kadeem reaches back toward George with both hands. In the next shot, Kadeem still has his left arm around Kit's neck.
While George is lying in the hole with the vehicle on top of him. Stallone comes to save him. The rest of the survivors come from the same direction as Stallone, followed by Amys character (Madelyne). 1. She was with Stallone when George fell into the hole so shouldn't she have came before the rest of the survivors. 2. Was George yelling at Stallone about the other side of the tunnel, did he have the other survivors in between him and Stallone, but that meant Stallone ran past everyone to get to George first. 3. Did the other survivors run past the hole with George lying in it to climb down the same side as Stallone, before Madelyne arrived.
When George looks at the security camera and tells the control room to cut the power, the camera glass has 5 cracks. When Kit looks at the monitor screen from the control room, the feed shows 7 cracks.
When George tells Ray Nord the tunnel is blocked off, Roy leaves to check out the damage for himself. His shadow is cast on the wall behind him as he walks down the tunnel toward the wall of fire. Another shadow of somebody running appears in front of Roy's shadow for a few seconds, then disappears.
When the fans are shut down so Kit can get into the vent system, he gets past the first fan, and it kicks on. The other fans aren't moving that fast. Once the first fan kicked on, the other fans should be spinning much faster due to fluidic coupling, similar to a torque converter in a car.
Grace (Vanessa Bell Calloway) and Norman (Barry Newman) were leaving for the night thinking everyone has died, before they find the survivors in the carpark. So how are they at the pier when Kit (Stallone), and Madelyne (Amy Brenneman) are rescued from the water. Everyone thought they had died. Did the rescue boat phone Grace and Norman to come and see Kit and Madelyne be saved.
At the beginning of the movie, two lanes of traffic go into the tunnel, with a solid, double yellow line between them. This road marking doesn't necessarily mean two lanes of traffic traveling in opposite directions, but that passing or changing lanes is severely restricted. Signs at the mouth of the tunnel say "Stay in Lane" and "Lane Crossers Will be Summonsed".
After blowing the manhole, there is now a direct entry to the ventilation system. Once the tunnel started filling with water, it would've leaked into the ventilation duct, cutting off the path for the the fresh air and suffocating any survivors.
The fireball turns almost every car in the tunnel to a burnt-out shell, breaking windows and body work and killing everyone. The flames are strong enough to flip cars, but do not penetrate the prison bus, even as windows smash as it rolls through the tunnel. Madelyne also survives, even though her windows are open. When she climbs out later, all of the pillars and window frames are badly burnt.
When Stallones character (Kit) is escaping from the tunnel collapsing killing Viggos character (Roy). Kadeem is standing over Stallone holding a big piece of concrete shouting something when the explosion sends him flying backwards, but what was the reason for going to kill Stallone with the concrete.
The survivors climb the stairs in the sandhog bunker to a small room below a maintenance parking lot. Since there were 8 steps to the hatch under the booth, then 20 steps to the parking lot, the lot was about 30 feet above the tunnel. The lowest point of the Hudson River is 93 feet deep, plus 10 feet of bedrock on top of the tunnel, so the lot would be under 60 feet of water.
When Kit goes through the first fan, they have to slow it down because it's going much too fast. When he gets to the other 3 fans, they are almost stopped as well. The fans are not connected; otherwise, they all would've started at the same time.
The goof item below may give away important plot points.
Kit inaccurately describes the process of a blowout. It would contradict the laws of physics for water and mud to flow upward under pressure according to Kit and Madelyne's plan to escape. Instead, the explosion would've cleared what remained of the tunnel for more mud, silt and water to fill it. There would no be upward pressure since the ventilation shafts had relieved it.