The camera then pans to rival Natalie, who was also filming at the location in Canberra.
Barr is seen awkwardly standing just out of frame, and Karl's caption reads: 'Suck it up haha.'
Sunrise's executive produce Michael Pell then jumped to Barr's defence, commenting: 'Very funny. Although unfortunately for you @karlstefanovic_ untrue'.
Pell later clarified that he and Karl are 'mates' and that the comment was meant as a 'joke'.
Karl's cheeky swipe at Barr comes as the Today show struggles to maintain its viewers, with Sunrise dominating the breakfast slot.