Somehow a scientist has created a "crack" in the fabric of the universe that leads back 85 million years ago to a much younger Earth. Okay, so when people go through the time portal, it's apparently a one way trip, with no way back. How do they know what is on the other side of the portal? At one point they show a "probe" they sent through first, remarking (in order to silence time travel critics like myself) that after sending the probe back 85 million years, they could not find it in the present (2149 AD) which led them to believe the past was a "different time stream." Well fine, pull a Star Trek.
Nevertheless, they warn travelers about to go through the portal that "the high oxygen levels on the other side (part of the reason insects and dinosaurs could get so big was that the atmospheric oxygen level in the Cretaceous period was much higher than it is in the current Neogene period) but how did they know this? Once again I ask: how did they know what was on the other side of the portal? Remember in the movie Stargate when they send a robot through the portal and try to track where it goes?
Some of the science and background in this show has been great; they completely kneecapped time travel critics when they proposed an alternative timeline. Most of the dinosaurs I've seen in the show are contemporary; shows involving dinosaurs often make the mistake of picking and choosing neat-looking/plot convenient dinosaurs at random while those dinosaurs might have lived on different continents or millions of years apart.
But here's the problem I really had: by my count they unloaded nearly 2,000 rounds at or into the attacking carnivorous dinosaurs in these two episodes and yet not a single dinosaur died, or even showed signs of injury. Were dinosaurs effectively bullet-proof? And if they were, why bother sending the "pilgrims" back with bullet-based weapons? Why not send them with tasers, RPGs and tanks or whatever it takes to bring down a Carnotaur? At one point in the episode, two characters unloaded fully-automatic assault rifles from a range of less than twenty feet at a dinosaur that stood roughly 7 feet tall. The dinosaur turned and fled, apparently unharmed by mere bullets.
Now, I'm willing to accept for the sake of this show's admittedly absurd plot that these dinosaurs have really thick skin. But five minutes after these two characters fail to stop the dinosaur with hundreds of bullets, another character mentions using tranquilizer guns. If a point-blank-range bullet will not penetrate the skin of a dinosaur, neither will a sub-sonic tranquilizer dart.
I realize that they can't think of everything when making a show, and when it comes to scifi shows (that over the last decade have shown an increasing special effects budget at the price of good writing) its hard to vet every single bit of every single episode. Nevertheless, the seeming bullet-proof aspect of the dinosaurs really bothers me, because the hulking, slow dinosaurs would have otherwise provided the "pilgrims" with a great source of protein. As the armored vehicle was being chased across a field with a Carnotaur right behind it (let's ignore the impossible biomechanics of a 50 mph dinosaur), unloading .50 BMG rounds into it from a turret and a dinosaur finally went down, I thought "that Carnotaur is going to be DELICIOUS!" and then the Carnotaur got back up, miraculously, and continued the chase.
That kind of firepower should cut through the engine of an armored vehicle. Not killing a 2-ton dinosaur with them is pretty stupid.