The windows on the car go back and forth between being up and down.
When the people see the dogs on the dock by the plane, the plane is safely tied up. About ten seconds later, when they look at the plane again, it is untied and way out in the river. There is no way the dogs could've chewed through the rope and let the plane drift that far out that quickly.
At about 58:00: Noah (Hill Harper) takes a bottle of wine from a rack whose bottles are covered in dust, but the bottle he examines is perfectly clean.
When the boys are in the garage they find a Mercedes covered in dust that has been parked for many years. When they try the key it starts immediately. Even if the car has great engineering, the battery would have gone dead years ago.
When Noah's giving his "let's get out of here" speech, he clearly jumps well before the dog comes crashing through the window to attack him, obviously expecting this to happen. This can be seen clearly at regular speed, and is even more profound in slow motion.
When Michelle Rodriguez is on the roof of the garage and pulling the rope, there are a couple of pairs of legs visible behind her, presumably crew.
The car wouldn't start not just because of the dead battery but because the gasoline being organic separates into components with time. The same applies to the gasoline in the generator that powers the house no problem, after that many years of being abandoned.
Good practice in maintaining any gasoline engine (car, generator, lawnmower) is to drain the tank before storing the machine for a long time.
The "german engineered" car wouldn't start up after a decade in storage, because lead-acid car batteries can only hold charge for months, not years.
When John and Matt descend from the attic, John pushes open a door to his right as if to surprise anybody within the room. This would make sense if the opponents were humans. But dogs can scent living creatures, so they probably wouldn't be surprised. If there were raging dogs within the room, it would be advisable to carefully open the door ajar and be prepared to quickly close it again.