Queensland State Archives posted a photo:
History of the Regional Courthouses: Mackay
The single story building contained rooms for the Judge, Police Magistrate, Barristers, Clerk of Petty Sessions, and Jury. It opened on 27 May 1886 and the first sitting of the Supreme Court was held on 15 June 1886. This building became a police station when a new Courthouse was constructed in 1938. Both bildings underwent refurbishments in 1990-1. The 1938 building is still in use, and the old 1886 building is being used mainly for storage.
Queensland State Archives Image ID 20895