This happened in front of us at the Quad City Airshow about 10:45 a.m.  I jumped up and down, waved my arms, I hollered to get his attention - but to no avail.  His exact words were, "I just forgot."  Besides missing the landing gear, it was a picture perfect landing - as you can see.  They brought out two fork lifts, raised the airplane and then put the landing gear down.  

Sent in by an ARC regular.