A real astronaut was on set during production as an advisor. Whenever he approached Roland Emmerich and said "That's not really possible," they told him to roll with it because "it's just a movie."
This is one of the most expensive independently financed movies ever produced, with a budget estimated at $138 million to $146 million. It is also one of the biggest box-office bombs of all time, losing almost the same amount once marketing costs were factored in.
Donald Sutherland gets prominent billing, including his own "And Starring" entry in the credits, but he only appears in a single two-minute scene.
The early sequence featuring Harper's family packing up and loading a moving truck while he's being grilled by government officials was a reshoot after initial filming had wrapped. Audiences really didn't understand what happened after the space accident so these exposition scenes are meant to answer those questions that otherwise didn't come clear until later in the film.
The idea for the film emerged during Independence Day: O Ressurgimento (2016) and the script was written over four years.