The scene was shot with a wide angle lens. It has what's called "barrel distortion". (As opposed to pincushion distortion.) Distortion in an image is defined as mapping errors between the object and the image. A rectangle in the object space should map to the image space as a rectangle. When its edges bow outward, as the do with a wide angle lens, the image has barrel distortion. If they bow inward, it's pincushion distortion. Arnett, if he were really there, can be thought of as the edge of that rectangle. He should appear bowed outward, just as the fellow on the other side of the scene is. Instead, his image is mapped out along a vertical line.
So, unless Arnett was feeling particularly swishy that night, there's no way he could have been present for the photo.
"unless Arnett was feeling particularly swishy that night..."
Isn't Arnett always swishy ?