Bairstow wandered out of his crease after leaving a bouncer and Alex Carey stumped him out.
Just before the lunch break on the final day, Bairstow got out in a bizarre manner. The English batter wandered out of his crease after ducking a bouncer from Cameron Green and Australian wicketkeeper Alex Carey stumped him out.
The dismissal has once again triggered the Spirit of Cricket debate, and McCullum believes Australia's actions will have a negative influence on the overall sportsmanship of the Ashes series.
"I imagine it will affect it, I think it has to. In the end, they made a play, they've got to live with that. We would have made a different play, but that's life," McCullum said, as quoted by ESPNcricinfo.
Australia won the Lord's Test by 43 runs and took a 2-0 lead in the five-match series. The hosts will have to win the remaining three Tests to avoid losing a Test series against the Aussies at home since 2001.
"From our point of view, we believe that we can still come back in this series, and that's where our focus has got to be. What I will say is it's a galvanised unit up there [the England dressing-room] and we saw the fight from the skipper, Broady [Stuart Broad] and the boys at the end there as well, which shows how much this means to the side. We'll lick our wounds and try and come back and rectify things," McCullum said.
"In the end, Australia won the Test match and fair play to them. It's just a shame that when you've got millions of people all around the world, and you've got a full house at Lord's, and you've everyone's eyeballs on this series, that for the next couple of days probably the most talked about aspect is going to be that [the dismissal] and that's disappointing," the coach further added.
England and Australia will square off in the third Ashes Test at Headingley from July 6.