Continuity mistake: In the scene where Hector is talkin to Samantha and Regina in the radio station, just after they met, Hector is taking off his gloves. Then they switch over to the girls and when they switch back to Hector, his gloves are back on and he starts taking them off again.
Continuity mistake: When Regina comes home the morning after the comet, there's nothing at the base of the stairs. As Regina takes Samantha outside to see that everyone is dust, Samantha finds the remains of their dog at the base of the stairs.
Continuity mistake: In the first scenes after the comet passes, they show the empty streets and there is a long shot of a car with its headlights on. When they zoom in to just show the car its headlights are off.
