Darryl Clough, 28, Andrew Moore, 37, and Marcus Hart, 25, bundled Glenn Mullen into a borrowed taxi before breaking both his finger and nose, the jury at Plymouth Crown Court was told.
The men threw the 46-year-old victim into a river in Plymouth at the end his hour-long ordeal on 31 March.
The trio were convicted because they filmed the attack - which took place to a soundtrack of the Swedish pop group’s biggest hit - and uploaded the evidence to Snapchat. The jury were shown the video.
All three men were found guilty of false imprisonment, while Mr Moore was also found guilty of assault occasioning actual bodily harm.
Mr Clough admitted punching and slapping Mr Mullen and telling his friend Mr Hart to bend back his fingers, which his friend did.
He said that they had pushed the victim into a river to “teach him a lesson”. Mr Clough claimed Mr Mullen was a drug dealer who had stolen money from them.
Mr Moore admitted driving his father’s taxi and told the court the group of friends had been out looking for drugs.
The driver also claimed that Mr Mullen was a drug dealer and was giving them directions to find crack cocaine and heroin at around 3am.
Police managed to make out the licence plate number of the Peugeot taxi in the video, linking it to Mr Moor. Detectives backed up the footage with CCTV coverage.
The Honourable Mr Justice James Dingemans said Mr Clough was “clearly the ringleader” of the attack.
But he agreed to postpone sentencing until 9 November at Exeter Crown court to allow time for a psychiatric report and a probation report on Mr Clough.
He remanded all three men until that date, telling them all sentencing options “including, inevitably, that of custody” would be considered.
Justice Dingemans thanked detectives for “the excellence of their investigation in a difficult case”.