Holders Hull ended up with just nine players on the field with Danny Washbrook, Jake Connor and Jamie Shaul all yellow-carded.
Winger Bureta Faraimo was also sent off in the last minute for a high tackle on Shaun Robinson as an otherwise enthralling contest descended into farcical scenes.
Championship side Featherstone – who famously beat Hull in the 1983 final – also had three players yellow carded along the way in a 38-20 defeat, FC eventually reaching Sunday’s quarter-final draw.
On that ending, Radford said: “It was fantastic, a great spectacle for Sky Sports.
“It had the 2007 Bransholme Dales versus Orchard Park Sharks game (a Hull amateur match) written all over it.
“And that’s no disrespect to either. Both are the most beautiful estates on the planet. I thought our energy and effort was fantastic but the finesse was horrible.
“We’ve got through but we’ve lost some more players to injury so that will give our medical staff a bit more to do. If they didn’t have enough.”
Hull lost Josh Bowden, Fetuli Talanoa and Carlos Tuimavave to injuries before the 50th minute.
Having trailed 30-10 at the break, Featherstone actually ‘won’ the second period.
Coach John Duffy admitted: “We were really poor that first 20 minutes or half hour. Our errors were really poor, sloppy errors.
“But we had a good chat at half-time about using the hill to our advantage and we did that.”
On what happened at the end, Duffy was asked if his side had got the Super League side “rattled”?
“I don’t think so – I just think it could have been handled a bit better by the official,” he said. “But I’ll leave it at that.”
On this evidence, Featherstone, third in the Championship, will fancy their chances of testing lesser Super League sides in the Qualifiers.
Duffy said: “Yeah, I think so but we have a lot to learn from tonight. We caused them some problems in attacking areas which is pleasing but we were chasing the game. It’s a learning curve for us but I’ll definitely take that second half into our next few games and we’ll look to play with that intensity.”
On two-try Luke Briscoe, who equalled a world-record by scoring for a 17th successive game, he said: “I’m sick of talking about him!
“No. I’m delighted for him. He was fantastic. He took his tries well didn’t he, great finishing.”