It was when the Queen sky-dived out of a helicopter with James Bond in her slipstream that you thought: hang on, this opening ceremony isn't quite like the other ones I remember.
Whispers had hinted that the start of the London Olympics might be a little eccentric, a touch more tongue-in-cheek than others we have witnessed.
What no-one expected was that it would be quite so gloriously daft, so cynicism-squashingly charming and - well, so much pinch-yourself fun.
From the moment the Red Arrows roared overhead to paint the town red, white and blue at 20:12 to Bradley Wiggins's unheralded yellow-shirted parade and the appearance of dancing NHS nurses - actual, real nurses - this was a constant swooping rollercoaster of noise, searing colour and what on earth was that?
Save the surprise? They barely stopped coming.
There was Mr Bean playing Chariots of Fire, on a keyboard, with one finger. There were skipping suffragettes and an army of Isambard Kingdom Brunels. There was a 60ft Voldemort, flying half-bird-half-bikes, flash-mob house parties and David Beckham driving a speedboat through a firework waterfall on Tower Bridge.
In the first three minutes alone we had Radio Four's shipping forecast, The Wind in the Willows's Mole and Ratty, Pink Floyd's flying pig and the EastEnders drum intro.
Did the rest of the world understand it? You barely had time to worry before another cultural reference hit you. Hold on - that's the Child Catcher from Chitty Chitty Bang Bang! There's 40 Sergeant Peppers! Was that a two-second clip from Kes I just spotted?
Opening ceremonies, traditionally big on pretension and po-faced, usually require a little mickey-taking to be endured. This one did it for you.
Four years ago Beijing had produced a night aiming to shock and awe the watching world with an unforgettable display of pyrotechnics and ostentatious expense.
London could never hope to match it, and so was set free to do something entirely original.
Watching it as a native was a strange and, for many, an increasingly emotional experience.
Unfurling in front of us was a whirlwind series of collective historical, cultural and social memories - the NHS, ska and rave, the Industrial Revolution, the Windrush, Great Ormond Street, the invention of the internet - which had Britons looking at each other and saying, hold on - that was us too, wasn't it?
It should have been jingoistic, or cliched, or obvious. Maybe to foreign eyes it was. But to those lucky 80,000 in the stadium and millions watching on television, there was something else, something not always felt: genuine pride in the little pieces of all of us that were being shown to the world.
It can feel too grandiose when people claim that sport can help shape new national identities. It's only a sideshow to the real stuff, no?
Not always. The multicultural France team that won the World Cup they hosted in 1998 changed that country's self-image for good. Beijing was China announcing that it was not only the present but the future.
We may have to wait a while longer to see if the London Olympics do the same for this host nation. But this was a Britain as never seen before - no simple Merchant Ivory fantasy, but a 21st century land of status updates, soap operas and a suburban red brick house with a single sulphur street light outside.
At one point Frankie Goes To Hollywood's 'Relax' was booming out. Banned from national radio within memory, here it was at the heart of a global showcase.
If you wanted to leave all that big stuff alone and just enjoy the party, the kaleidoscopic soundtrack carried you there. The Pistols and the Who, Dizzee Rascal, Underworld, the Specials and the Jam, New Order and then Macca. Get your ears round that, alternative-world Paris opening ceremony.
There were neat, sensitive little touches - Stephen Lawrence's mother Doreen helping to carry the Olympic flag into the arena; Muhammad Ali, held upright by his wife Lonnie, being there to receive it; 500 workers who had helped build the stadium forming a guard of honour as Sir Steve Redgrave jogged in with the flaming torch.
And the big stuff?
The cauldron, hidden all evening, constructed from 200 copper petals brought in by the world's parading flag-bearers, was a thing of genuine beauty. That it was lit by seven young athletes nominated by Britain's seven greatest Olympic medallists was both the biggest revelation on a night of surprises and perfectly in keeping with the ethos of the bid.
Inspire a generation, London 2012 chairman Seb Coe had told the International Olympic Committee seven years ago. Here he was, delivering both on that promise and several more.
"This is our time," Coe declared to the cheering stadium. IOC president Jacques Rogge, judging his audience with an expert hand, followed suit: "In a sense, the Olympic Games are coming home tonight."
London, of course, has done Olympic opening ceremonies before, but never like this.
The highlight of 1908 was a display by gymnasts from the London Polytechnic. In 1948, Wembley heard Army bands play, the Royal Horse Artillery fire a 21-gun salute and 2,500 pigeons squawk off into cloudless skies, to pester Londoners with their offspring for decades to come.
If that was a different London, so is this little patch in Stratford unrecognisable from the rest of the modern city.
Walking around Olympic Park in the past few days has felt gloriously unreal - towering new stadia where once were fly-tips and blight, wildflowers and green riverbanks rather than jam-packed city streets, perfect blue skies in a summer of filthy grey and flood.
Friday night was the moment it all began to make sense, even as the ceremony left those watching giddy: it's here, it's actually here.
The sense of the unknown now stretches into the 16 days ahead. Superstars like Usain Bolt, Michael Phelps, Kobe Bryant and Sir Chris Hoy will once again strive to show us the impossible, but so too will new heroes. Fresh tales of triumph and disaster will emerge that we can as yet only guess at, new memories and legends be made.
"We're a warm-up act for the real show coming up," ceremony director Danny Boyle had said to the crowd, minutes before his surreal, splendid shebang blasted into life.
He's right. But if the spectacular that lies ahead matches the support act, these Olympics will leave an impression that no-one who witnesses them is likely to forget.