20 Things You Didn't Know About Alien 3

20. The Facehugger Wasn't Meant To Impregnate A Dog

Early on in Alien³, we learn a facehugger has impregnated the dog of one of the convicts. Director David Fincher thought it would be cool to have a Xenomorph-dog hybrid for a change since he wanted the alien to be inhuman and have the look "more of a puma, or a beast".

However, the original plan was to have the facehugger lay its egg in an ox. Only in mid-production did Fincher feel the alien would move better if it had the characteristics of a smaller, more agile creature. It would also be more convenient, since an ox would be a nightmare to transport and easily rattled by the constantly shifting sets. This last-minute change was frustrating for the crew and producers since the ox birth scene had already been set up and filmed by the time Fincher made this decision.

Sadly, this was just one of many, many major inconveniences that occurred on the set of Alien³.