Labour leader Jens Stoltenberg won global press coverage for the video of his shift, which shows him light-heartedly chatting to his customers, and hearing their concerns.
But the coverage started to sour when the background to the video came to light.
"They're five ordinary people who were asked if they wanted to take part in a video for the Labour Party and who knew nothing else, except that they were going to be picked up in a taxi," Pia Gulbrandsen, a spokeswoman for the Labour Party told AFP. "Their spontanaeity was real when they realised that the driver was the prime minister."
Each of the five received 500 kroner (65 euros, $85) from production company Try, run by Kjetil Try, who is known to be a close friend of the Prime Minister.
The opposition has been quick to jump on the revelations, with Bård Hoksrud, transport spokesman for the Progress Party claiming to feel "cheated".
On Monday night Jens Stoltenberg said he had not known his passengers were paid.
"I did not know that when the film was made, but I learned that they were paid afterwards," he told VG. "That was the decision of the production company. They told me that it is normal, and I trusted them and believed that it must be OK."
Several of the passengers were in fact picked up randomly from the street, he added, and none knew in advance that they would be driven by the prime minister.
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"No one who came into the taxi knew that I was the driver. And that was the whole point," he said.