Vehicles were left stranded in mud at the park-and-ride site for the Portmeirion event on 4 September.
Organisers have defended criticism, saying they were not warned against using the site.
Porthmadog council has now called for the Welsh Government to carry out an inquiry into the problems.
The Welsh Government, which provides funding for the festival, said, as with all such events, it would be "conducting a full post-event review, with the event organisers and local partners" in due course.
Tractors had to tow hundreds of stranded vehicle clear, with some festival-goers forced to take refuge in a makeshift shelter at Porthmadog's Glaslyn leisure centre overnight.
Both Natural Resources Wales and Gwynedd council have said Festival No.6 organisers knew the park-and-ride facility was on a flood plain and had been warned of a flooding risk.
Speaking after a town council meeting on Tuesday night, councillor Simon Brooks said there remained many unanswered questions.
"We know the festival organisers had some responsibility but we also know there were different agencies involved - Gwynedd council, the police, Natural Resources Wales - and we've heard many different stories over the past few days," he told BBC Radio Cymru's Post Cyntaf programme.
"As a council we need to know exactly what happened and what decisions were taken which led to the problems."
He pointed out there was a lot of local support for the festival and that it brought economic benefits to the town and surrounding area.
Calls for an independent inquiry have been made after hundreds of visitors' cars became stuck at a car park at Gwynedd's Festival No.6.