While spectators at Sapporo Dome witnessed an entertaining Rugby World Cup Pool D opener between Australia and Fiji on Saturday, a number expressed concerns about crowd safety following the game.

Many fans making their way from the 41,410-seat stadium following Australia's 39-21 comeback win were forced to endure a long wait to reach the exits, with a limited number of doorways causing major bottlenecks.

A number took to social media to complain about the potential safety hazard, urging organizers to improve the flow of spectators ahead of Sunday's match at the venue between England and Tonga.

Keith Davies, a rugby coach originally from the United Kingdom, spent more than an hour stuck inside a walkway in a lower level of the stadium waiting to reach the exits after the game between Australia and Fiji.

"There were just two doors open and thousands of people trying to get out," Davies said on Sunday.

"In a situation like that, something like the Hillsborough disaster is just waiting to happen," he said, referring to the fatal crush that claimed 96 lives at the Hillsborough Stadium in Sheffield, England, in 1989.

"I've been in a few stadiums in my lifetime, and yesterday just wasn't a safe situation," said Davies, who works as forwards coach for Japanese Top Challenge League side the Kamaishi Seawaves.

A video shot by Davies and posted to Facebook shows a corridor and stairway inside the stadium, which is home to the Nippon-Ham Fighters in Japanese professional baseball, packed with fans unable to make progress toward the exits.

Agitated fans can be heard yelling for staff to open more doors.

Several commenters responding to the video echoed Davies' sentiments.

"It was unsafe and a complete review of evacuation procedures is needed before tomorrow's game," wrote one.

"It was a debacle. As was getting a beer. Good game though!" said another.

As the England-Tonga match was drawing to a close, an official Rugby World Cup Twitter account posted an advisory to fans.

"We remind fans @ #RWCSapporo that post-match crowd flow is managed to control the onward flow into the local metro station."

"Fans may be briefly held back in parts of the stadium. Spend some time in the stadium after the match to let the crowd clear."