Not strictly an airshow, but close enough perhaps...
April '98, Cottesmore, AOC 1 Group is visiting to view the display routines by 'his' aircraft before signing the crews off to display for the forthcoming season. I was holding at Cottesmore, working for the GR1 display crew as jack of few trades, master of none, and it had been my job to film the display practices; on this day, I was to film all three displays (GR1, Jag and Harrier).
Unlike previous days, when I'd had the flat roof outside ATC to myself during the filming, lots of people had gathered to watch proceedings, from the AOC and his flunkies down through all 3 relevant stn cdrs, sqn bosses, hangers on etc etc. The weather was reasonable, but with a fair breeze blowing across the runway. The Harrier taxies out and lines up, just as the door from the VCR opens and another holding bloke appears carrying a large tray with refreshments for the throng. On his tray are teacups, saucers, teapot, milk jug, sugar bowl, teaspoons, biccies...and about 50 pristine serviettes. He takes two steps across the flat roof when the wind catches the serviettes and instantly creats a snowstorm heading rapidly for said Harrier.
Cue banging on window of VCR and pointing at snowstorm to make them hold the Harrier on the ground while the BCU et al dash all over the airfield trying to gather up all the serviettes. Fortunately the Harrier still had enough fuel to launch into his display even after 10-15 mins of holding. Having been something of a sh1t magnet during my hold, I was delighted that someone else had made a faux pas for once...