The dust masks worn by the four characters are used for construction. They can stop dust particulates but would do nothing to prevent any airborne viral or bacterial agents from entering a person's respiratory system.
When Bobby rids herself of her "infected" shirt she slides it directly below the SUV where she is sitting, barely underneath her seat. But when the SUV drives away it only has to go a foot or so before the shirt appears directly in the middle of the rear tires on the road.
At the golf resort, when Brian nearly falls into the pool and is clinging onto the spring board, the latex glove on his right hand splits revealing his little finger. In the next shot when Danny pulls him back onto the board the glove is in tact.
In the beginning scene when the camera is turned upside and the car is coming. You can see the yellow lines on the road and only those, but suddenly when it changes scenes and says Lou Taylor Pucci, another line magically appears next to the other line on the road.
At the golf resort, characters cock their shotguns, indicating they've been walking around with unloaded weapons. Then they keep cocking them. No live rounds are heard hitting the floor, so evidently they're all carrying empty weapons.