The trio were seen placing the trolley on top of the Balclutha Road Bridge, known as the Clutha Bridge, early on Sunday morning and police have released photographs of the trio and their handiwork in an effort to track them down.
They wheeled the trolley from a nearby supermarket to the bridge, which spans the Clutha River on State Highway 1, about 5.30am on Sunday and were caught on camera in various stages of their mission.
While the incident might have been considered a harmless prank by those involved, charges could be laid along the lines of reckless endangerment, Sgt Parsons said.
"These incidents are extremely dangerous as a trolley could fall on to a passing vehicle or motorist, and that can cause a serious crash that could kill someone."
Although police did not allow members of the public to comment on their Facebook post appealing for information, it was quickly spread around the community and not everyone seemed to share the authorities’ displeasure with the stunt.
Others said it was "quite impressive" and they couldn’t help but laugh.
Police do not share this amusement and are "working to identify those responsible", calling on anyone who recognises the people involved or has any information on this incident to contact them on 105 and reference file number 230308/8290.
- Additional reporting Oscar Francis, ODT