You will see them mouthing fake conversations, pulling fake files, scribbling imaginary diagnoses, and generally trying to move about like people in a hospital do. They are, however, not in a hospital.
Gervais asserts that he plays a character on stage, ironically presenting himself as better or more knowledgeable than the people in the seats. But it's a bit harder to laugh along with the school bully than it is with the class clown.
Gervais and his co-writer/director create one premise, then seem to shift to something else - and then to something else again. But the conceptual problems are less troubling than the essential shortage of laughs.
Waltz with Bashir was not made for Hollywood, it was made for human beings. It was made for the people who went through the horror it shows.