Right, the kids fixing the car.
Let's assume the batteries work, the tyres aren't rotten and the engine won't have seized up etc.
Zach know's how to fix this car because they helped Grandpa fix a Malibu once? Really? I helped my Dad build a shed once, now I know how to build a shed from trees!
Now, surely, it would have made more sense to have Zach be into fixing cars in the first few scenes of the movie? Perhaps replace the pointless girlfriend scene with him in a garage tinkering with a car? So, his skill in fixing cars makes sense when it comes to fixing the Jeep?
And Grey, mad keen on dinosaurs, but never needs to use his ridiculous in depth knowledge once..? Apart form to say "that's not a real dinosaur" near the end?
Surely, at some point during the pod scene and in the forest etc, he would be able to say something like "Oh, The diplotricersaurus has a brilliant sense of smell, or uses vibrations to sense movement" using that knowledge to escape danger... ANYTHING!