He said during an appearance on US chatshow Jimmy Kimmel Live!, guest hosted by McElhenney: "I remember seeing Blake and saying, 'I have bad news and I have really bad news.'
He jokingly continued: "I slipped into someone's DMs again.
"[But] the really bad news is that I might have bought half of a fifth tier national football league in Wales."
The Deadpool actor then admitted the former Gossip Girl star hit the roof, adding: "We are still working through that one."
Reynolds bought the Welsh club McElhenney in 2020 and has since filmed a documentary Welcome to Wrexham, which follows the pair's football journey in the town.
The documentary will start streaming on August 25 on Disney Plus, FX and Hulu in the UK.
The 45-year-old actor also shared that he met Rob initially on Direct Message on Instagram and they built a partnership from there.
The pair also admitted that their lack of football knowledge has led to former footballer ace David Beckham openly mocking them for not understanding the offside rule.
Beckham, who joined them in a box at a game, was stunned when they accidentally cheered while their team was struggling.
"We were cheering," McElhennney said. "We looked over at Beckham. He was just shaking his head."
Reynolds also admitted that he wasn't even much of a football fan when he purchased the club.
"I understand the absolutely gorgeous disaster, slow motion train wreck that is the sport of football," Ryan said. "I'm obsessed now."