When the group is leaving the camp Bellamy says that there are 18 people dead. Clarke says that 82 are alive. However since Bellamy snuck on the ship and Raven came down afterwards there were actually 102 people. So Clarke should have said 84 people alive.
After the destruction of Ark, Jaha is in Earth Monitoring Station that is not spinning to create artificial gravity but despite that he's not in a state of weightlessness.
The remaining fuel of the drop-ship burn the lot of attacking grounders to the ground, while the space children in the drop-ship were sound and fine without being seared to proper meat. And the drop-ship was once blown a hole on it due to the evil Murphy in previous story lines.
After Jaha told Abby, "Find the rest of our people, Abby. Find Clarke", the background music runs. But in the mix of the background sound we can also hear female voice yelling "Bellamy" which was a mistake.
When the Mecha Station lands on Earth in the Eastern U.S. and Abby first emerges to view the scene, the snow-capped mountains in the background are part of the Canadian Rockies, not the Appalachians.