At least 20 actors were on the two-story stage when it crumpled at the Cinespace Film Studios in the city's west end, the Toronto Star reported.
Police and first responders were taken off guard when they arrived about 8 a.m., as most of the actors were made up as zombies and covered in fake blood, the report said.
Peter Macintyre, a spokesman for Toronto Emergency Medical Services, said the injured were taken by a fleet of ambulances to four different hospitals.
Hours later, it emerged none of the injuries were serious.
The film's star, Milla Jovovich, wasn't injured and filming is scheduled to continue through Dec. 23, CITY TV reported.