Not quite a "cock up" but definately a "whoops".
Many years ago I was "volunteered" to take part in a guard of honour for a little ceremony in a lay-by just off the A98. The site was close to a wartime airfield from which Mosquito aircraft flew some daring missions, and to mark the significance a memorial was being unveiled in the aforementioned lay-by.
To describe the topography, the road was higher than the lay-by, and the fields to the side of the lay-by swept down quite a bit, so by the time the guard of honour were in position we could see through the trees which lined the lay-by and down over the fields.
Part of the ceremony was to be a fly past by a Mosquito, which was either one of the few remaining or the last survivor, and was timed to coincide with part of the ceremony. The lay-by was crowded with locals, old aircrew who had flown out of the airfield and some of the local dignitaries, all looking at us and with their backs to the fields.
When the time approached for the fly-past the guard of honour were searching the skies for the approaching Mosquito. Remember we could see what was happening , the crowd couldn't, so when the Mossie roared overhead at max-chat and what appeared to be 50 feet, there was much confusion in the crowd and a couple of local dignitaries harumphing around the place. Good job the local police closed the road for the actual service..
Mind you the old boys were walking around with great big smiles.