Amid the fallout from England's pool stage exit has been the suggestion that Farrell championed the cause of fellow rugby league convert Sam Burgess, while questions have also been asked of his objectivity in the fly-half debate involving his son Owen, who was preferred to George Ford in England's key games against Wales and Australia.
"There are no players in the selection meetings," Farrell told reporters on Monday after number eight Billy Vunipola was mentioned as the originator of the claim.
"The four of us as coaches get together and have discussions and ultimately Stuart makes the call and we all buy into that."
Farrell, a straight-talker in his dealings with the media, then appeared somewhat taken aback to be asked about his involvement in the selection of his son and dismissed the question with a curt "come on".
He was far more forthcoming on the future of Lancaster and his assistants in the wake of England's first-ever pool-stage exit.
"We've lost two games and people will try to define us by those two games but what Stuart has built is more than that," he said.
"This whole campaign and the three and a half years of his leadership has been built on rock solid foundations. He has done marvellous things for this country and this rugby team and I thank him.
"We've had some big wins and some losses but Stuart's ability to bring a meaning to white shirt is second to none.
"He's the proudest and hardest-working Englishman I've ever known and it's a privilege to have worked with the guy."
England head coach Stuart Lancaster has called on the country to stay behind his players
Image credit: PA Sport
Farrell said, as Lancaster did on Sunday, that he would await the post-tournament review before any decision was made on his own future but urged the Rugby Football Union to keep faith with the head coach.
"He can't be fired because there's too much hard work that has gone into this," he said.
"I think he's a brilliant coach who has done wonders for this team and connecting everyone back to this team.
"There will be things he will take from this experience and become a better coach.
"The team are a young group who will win trophies in the future and we would all like to be part of that.
"We have to man up and learn from this pain. I want to be better as a coach and sit here in however many years and say I got better from those dark days."
Farrell said the squad would have to "man up" for their final fixture against Uruguay in Manchester on Saturday.
"It's not a great situation for the fans," he said. "But we will try to put on a performance that will put a wry smile on some faces."