Theme park Six Flags Great Adventure had to shut down much-hyped 4D roller coaster Joker after two riders remained on their seats for 15 minutes on the day of testing. It is advertised as a four-dimensional (or 4D) free-fly coaster that is able to flip riders upside down for the whole ride in the New Jersey park.

Joker, named after a Batman villain, was noted as rocking too much without returning to the station in the right position. Six Flags spokesperson Kristin Siebeneicher told Yahoo News that they are now making a minor change to minimize the ride's rocking.

The two men had to stay on their seats until operators released harnesses. The park then shut the ride down and made the important maintenance. Siebeneicher said the two men were safe and uninjured. She added that the ride is running fine now and is had no flaws when a camera equipment was attached onboard for a promotional shoot.

Joe Bracco, one of the men who got stuck told NJ.com that the ride "swings back and forth so much" that their momentum just got their cable car stuck. They were definitely not in the position that they should be at then of the ride.

Six Flags chief executive officer John Duffey told CNBC that the 4D virtual reality roller coaster Joker would provide a "more immersive experience for riders." Adding virtual reality to the roller coaster attraction would transform the older ride into "a great new experience."

The addition of virtual reality to Joker costs the company only less that USDS1 million. It was originally called "Total Mayhem". It is Six Flag's 14th roller coaster ride.

The said incident has not affected the operations though. As planned, Joker would still open the ride to season pass holders on Friday and the general public on Saturday.