West Yorkshire Police said it had asked for the club's premises licence, which allows it to serve booze to fans, to be reviewed by Wakefield Council.
The rugby league Championship side said it was co-operating with the authorities.
Rugby League Live reported on March 31 that some Rovers players and staff had allegedly mixed and socialised in a bar at the Millennium Stadium, following their Challenge Cup win at home to Batley Bulldogs four days earlier.
Covid restrictions at the time banned pubs and non-essential shops from trading beyond a delivery service, while indoor gatherings were illegal.
In a statement on Wednesday, West Yorkshire Police said it was "aware of a reported breach of coronavirus restrictions at Millennium Stadium, Featherstone, on Saturday, March 27, and has been working alongside the Rugby Football League (RFL) in ensuring this is investigated and appropriate sanctions put in place.
“As a result of information that has come to light as part of these enquiries, West Yorkshire Police has instigated a review of the premises licence.”
The matter could now be decided by a public hearing, where a panel of three councillors would decide what action, if any, should be taken against the club.
If that happens, they would have a range of options available to them, including revoking the licence, suspending it for a short period of time, or issuing the club a warning with no further punishment.
Any decision could also have a bearing on whether alcohol can be sold at Wakefield AFC games, as the semi-pro football club also uses the Millennium Stadium as its home ground.
The premises licence covers all events held at the venue, on Post Office Road in the town.
Featherstone Rovers CEO Martin Vickers said that the club, "Is co-operating with the appropriate authorities in dealing with this matter."
He added: "The police have confirmed that there will be no charges for any individuals in respect of any potential Covid breaches and we will continue to work with the police and others in dealing with any future reviews."
The RFL, the sport's governing body, said its investigation was ongoing.
Local Democracy Reporting Service