I recently watched Spotlight in a cinema in Sydney and it had been cropped to 2.35:1 from its original 1.85:1. The same thing happened when I watched Boyhood in 2014.
I emailed the cinema chain regarding this and they replied:
"All films are sent to us directly from the distributor and in the format and viewing that they intend the film to be shown. Unfortunately, this is something that we do not have control over."
Is there any reason why 1.85:1 films might have been distributed in 2.35:1?