Publicity for this film in 1980 stated that this movie was the most expensive film ever made in Australia. Reportedly, this picture had a budget of $5 million (Australian).
This film's executive producer Stephen W. Sharmat once announced a series of seven Australian-American movies to be filmed in Australia with plans to raise $45 million in finance from investors in Australia and overseas. The Earthling (1980) was the first of these pictures and was the only one that actually got made.
A number of Australian actors who appeared in this movie, including Jack Thompson, had their voices dubbed for the film's American release in the USA.
This was the first film featuring Australian actor Jack Thompson that was theatrically released after Thompson won the Cannes Film Festival Best Supporting Actor award for Breaker Morant (1980).
According to the book 'The Films of William Holden' by Lawrence J. Quirk, director Peter Collinson was allegedly very tough on then child actor Ricky Schroder during filming to the point that co-star William Holden intervened. The two formed a close relationship and Schroeder about 12 years later in life, in 1992, named his son Holden Schroder after him.