"The brown snake [Brisbane River] hasn't been this colour for a long time," one user said.
Another added: "Well, I'll be damned. If that isn't the fakest, worst photoshop job I've ever seen …"
Since it was uploaded to Reddit a day ago, the photoshopper has "coloured in" the error, even giving the river a murkier look, compared to its previous attempt of crystalline blue.
Despite the error, the apartment boasts a contemporary interior design and open-plan living between the lounge room and kitchen, providing great entertainment value.
"Imagine the views from here. Sit back and watch the City Cats cruise by or the night glow from the city. You simply have to view this in person," the ad reads.
When news.com.au contacted a Ray White agent if they'd changed the photo, he wished "not to comment".
The Sanford Street property is due to go to auction on December 8 with the median price for a three-bedroom apartment without a water view set at A$670,000 ($714,024).