Many fans might have been distracted by the anticipation ahead of The Killers performing "Mr Brightside", but others spotted the comedian sweeping the stage while the band took a brief break.
Confused viewers posted on Twitter to check they weren't hallucinating, with one writing: "Did Jimmy Carr just sweep the stage for The Killers to come back on?"
Click through the gallery to see the best pictures from Glastonbury
Others wondered if the heatwave the UK is currently experiencing had finally got to them.
"Either Jimmy Carr just swept the pyramid stage at #Glastonbury2019 followed by The Pet Shop Boys joining The Killers on stage... or the heat in the kitchen at work today has finally hit," another commented.
Carr wasn't the only guest appearance during The Killers' set. They were also joined by Pet Shop Boys for a rendition of "Always on My Mind", and Johnny Marr for a rousing performance of "This Charming Man" by The Smiths.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies