"Some photographer just ran straight in front of me straight after the finish line. I don't know what he was doing," the Danish rider told reporters.
"Yeah, I went down. People in the finish area should use their eyes a bit more."
Vingegaard, who did not appear hurt, finished two seconds behind overall leader Tadej Pogacar and stayed second, 4:15 off the pace.
Catch up on the action from stage 16 in our full report here.