The incident came after five minutes at the Stadium of Light and is likely to remain a major talking point for some time.
Bent's shot from inside the box struck the large red beach ball, which had "Liverpool" emblazoned across it, and the match ball was clearly deflected away from goalkeeper Pepe Reina as well as making things awkward for defender Glen Johnson.
Liverpool's players protested but the goal was allowed to stand.
The rules state the referee has the option to allow play to continue if a "second ball" goes on to the field but should call a halt if it interferes with the action.
It also states he should stop the game in the case of "any kind of outside interference" but in reality matches are routinely allowed to continue with items like balloons on the pitch.
"If that's the case then we've got away with one," Sunderland boss Steve Bruce told the BBC.
"I didn't know that was the rule to be honest. I hope that doesn't become the main issue as I thought we deserved to win overall, but I'm sure it will."
Bent, whose goal took his tally to six in five games, said: "The beach ball was sitting there in their six-yard box so if they leave it there they pay the penalty."
"I was surprised as the linesman was there," said Benitez. "The players explained it to me but you cannot change it."
"We didn't play well and we didn't have the luck with the goal so altogether it was difficult," said Benitez.
"We had some chances, but not very clear, and they did too on the counter-attack."
"Chelsea have lost two games, people say that it's impossible if you lose four ..." he said. "I think this year the top sides will lose (more) games and I think there will be more competition."
