In the damaged bridge scene, the shots taken from on the bridge show a large lake on both side of where the characters are standing on the bridge, while shots taken of the damage from further away and from above show the bridge spanning rapids in a river.
During the crossing the bridge scenes there is a person clearly visible in the distance, standing up, wearing a high visibility jacket. This person should be lying on the ground as they would have been poisoned by the gas. It looks like a crew member ensuring there is no moving traffic visible whilst the scenes are being shot.
When the character Tye leans over a "dead" character she blinks her eyes. Happens in a house. Don't want to reveal too much.
You can clearly see after one of the characters is said to be dead he is breathing. Seen near end of movie. Don't want to reveal too much.