With Hull in complete control, the game turned ugly after 50 minutes as both sides showed their boxing skills. Referee Steve Ganson sent off Hull's Danny Tickle and Castleford's Weller Hauraki, while sin-binning Justin Carney and Mark O'Meley.
"When the match review committee have a look at it, I think there will be a few people who will be quite nervous, not all our players," Gentle said. "I was impressed how they stuck together and it was good to see them unite."
There was bad news on the injury front for the home side. "It looks like Aaron Heremaia has broken a rib and he will be going down to the hospital shortly," Gentle said. "That's all we know about that."
Gentle praised the work of home "conductor" Daniel Holdsworth on his return from a two-match concussion absence, as his kicking game put the Tigers on the back foot.
"It was a performance for us; the way we played (in losing to Widnes) last week was ordinary. We copped a fair bit of flack about it and deservedly so," Gentle said. "It was more of a performance of pride, we know we are better than what we served up (at Widnes)."
On Holdsworth, Gentle said: "He's our conductor isn't he. You can see that in the last fortnight we have really missed him. We got him off early tonight for precaution."
Castleford head coach Ian Millward admitted to feeling disappointment at the amount of errors his side made.
"It wasn't a great start and we were down 22-0 at half-time from high kicks and an intercept. Obviously in the second half we capitulated," said Millward. "We need to just put that one to bed. Every try for them was off an error by us, but we should have done better in the second-half to regroup from that.
"I felt sorry for Weller. He (Tickle) has hit him twice. What is he supposed to do, just stand there and get a broken nose and a broken cheekbone? I don't understand that one, the interpretations are interesting and that's for both sides."