The doorknob on the door leading to the basement in the living room switches sides a few times.
While at the airport bar Roger has a spiderweb tattoo on his right elbow. This is the only time that it is seen.
The Smiths are seen rising from a hibernation on day 3 of their space travel. This would not be necessary since the space-station can be reached in only hours after launch.
There was no reason for Klaus to call for help, only to tell Steven to run away when he runs to help.