If they had been at the Sermon on the Mount when Jesus brought forth the miracle of the loaves and fishes, they would have thought "Did he wash his hands? Where are the napkins? How long was that fish cooked?"

The Loaves and Fishes thing was at a different event from the Sermon on the Mount. Or maybe two different events. But definitely not the Sermon on the Mount. Unless it was kind of expected by then so nobody bothered to mention it...