Jakub Hudlický, the action coordinator for the Resident Evil film, released rehearsal footage of the combined creature, showing how the actors explored the movements of this human-assembled monster. The actors' performances provided a foundation for production, while the final on-screen appearance was completed using CGI. After the film set records during its opening weekend, crew members involved in the production began sharing behind-the-scenes footage.
Hudlický stated that the team's initial challenge was figuring out "how the combined creature should move." In the footage, performers are connected by straps as they attempt jumps, rolls, and stumbling movements, searching for actions that could be performed collectively by several people.
Director Zach Cregg initially attempted to create the creature using live actors. He strapped five performers together and had them attempt continuous sideways rolls, with some required to remain inverted at all times. Cregg felt this approach lacked sufficient flexibility and that the performers' heads would be visible, failing to achieve the desired effect for the film.
The production team ultimately used CGI to render the combined creature; other monsters in the film were created using practical effects.