Mostert's Prodrive Racing team said that surgery had been delayed until Saturday morning due to a "more urgent case" at Orange hospital.
Mostert is expected to be ruled out for the rest of the season with five rounds left. The three officials were cleared of serious injury.
V8 Supercars officials confirmed on Saturday that they would investigate Mostert's crash with Prodrive Racing after the Bathurst 1000 round in a bid to improve safety.
"We can always learn something from what has happened and how to prevent other things happening in the future," V8 Supercars technical director David Stuart told speedcafe.com website.
Fans have begun signing a "get well soon Mozzie" wall near the merchandise stalls at the track in a huge show of support for Mostert.
- AAP