An express train traveling at 70mph that is closing from 100 miles behind on a cargo train traveling at 15mph in the same direction will take 109 minutes to reach it not the 58 minutes that Gina calculates.
Sam and Rosie are waiting, while Vic and the other guys are trying to kill the aliens on their first attempt. Sam shoots a few rounds, and we can see the bullets holes onto the door. Minutes later, when Vic comes back to them, the holes has disappeared.
While inspecting the burning car, Vic Holden claims that he can smell methane. This cannot happen - methane is odorless. When it is supplied as natural gas into buildings for gas appliances, another chemical, usually ethyl mercaptan, is added to the gas to give it a distinctive odor that lets people know when a leak occurs.