Cairns Aquarium cohabs a lot of their reptiles with other animals, both with other reptiles and nonreptiles.
Green Tree Python is mixed with Green Tree Frog, Eastern Rainbowfish and Redclaw Crayfish, and in another tank, Green Tree Python is mixed with Eastern Snakeneck Turtle.
Fly River Turtle is mixed with Jardine River Turtle, Stirling's Snapping Turtle, Eastern Snakeneck Turtle, Eastern Rainbowfish, Guppy and Redclaw Crayfish, and in another tank, Fly River Turtle is mixed with Rock Flagtail.
Freshwater Crocodile is mixed with Krefft's River Turtle, Coal Grunter, Forktail Catfish and Snakehead Gudgeon.
Bluetongue Skink is mixed with Frillneck Lizard.
Emerald Tree Monitor is mixed with some kind of skink.
Common Tree Frog is mixed with Stoney Creek Frog.
Some kind of snake (I think Keelback Snake) is mixed with Firetail Gudgeon.
juvenile Saltwater Crocodile with Striped Scat.
At one point there was a Krefft's River Turtle in the river monsters tank (which I only ever saw in there once, I don't know if it's still in there or not), which means it was mixed with Freshwater Whiptail Ray, Mangrove Jack, Barramundi, Gulf Saratoga, Sooty Grunter and Barcoo Grunter.
Hartleys Crocodile Adventures also has a few mixed reptile exhibits, including
Freshwater Crocodile + Kreffts River Turtle
Sawshell Turtle + Jabiru
Radiated Tortoise + Rhinoceros Iguana
juvenile Saltwater Crocodile + some species of aquatic snake + juvenile Barramundi + juvenile Indo-Pacific Tarpon
Reef HQ has a mix of juvenile Saltwater Crocodile with Barramundi and Strawberry Land Hermit Crab. they also mix some kind of freshwater turtle (Krefft's or Sawshell I believe) with rainbowfish and freshwater shrimp. they used to have Green Sea Turtle with a variety of sharks, rays, sawfish, large fish and small reef fish, but the sea turtles have since been taken off display.
AQWA has at one point mixed Flatback Sea Turtle with various sharks, rays and fish. I don't know of they still have this mix.