When Charlie stumbles out of the bathroom stall at around 16:25, he accidentally, visibly moves the prop sink.
(at around 8 mins) There is a camera in the top right corner of the screen.
Around 14:30, right after Dennis asks Mac if his voice sounds like someone who needs to go to the hospital, watch Mac in the mirror. He starts cracking up and the very next shot of him shows him looking sick and about to puke too.