But some eagle eyed viewers - with a little help from Sky+ - reckon that not everything was as it seemed.
Andrew, a full-time illusionist from Malaysia, was among the hopefuls who auditioned on Saturday's episode of the ITV show.
"It's always a dream to be on Britain's Got Talent, and perform for the royal family," he said.
The 30-year-old began by announcing that his performance involved a card trick with his own twist - "a sense of danger".
He invited Ant and Dec on stage before asking Dec to pick a random card. Placing a board over Dec, Andrew then blindfolded himself before asking Ant to throw the cards up in the air.
Andrew hurled the knife in Dec's direction, for the knife to successfully pin Dec's card to the board.
Or so it seemed.
Thanks to modern TVs, some viewers weren't quite convinced.
"Watch in slo-mo the knife appear from nowhere in the knife-throwing act on #bgt with Dec @antanddec," one viewer wrote on Twitter during the show.
Another accused: "If you’re wondering, he didn’t actually throw the knife. Straight down his sleeve. The (forced) card and knife popped out of the prop around Dec’s neck #BGT #BritainsGotTalent."
And a third (via OK! Magazine) agreed: "He never threw no knife. That popped out that box by a button #BGT #BritainsGotTalent."
Whether or not those people are right we've no idea, but what is sure is that Andrew's trick and showmanship proved a hit with the judges.
"I love the fact that it was really intense," said Alesha Dixon. "Your presentation is fantastic."
With four yeses, Andrew was put through to the next stage.
Other acts in the weekend's episode included exam invigilator Noel James who performed a stand-up routine.
Donchez Dacres took to the stage with his original song ‘Wiggle Wine’, 90-year-old Audrey Leybourne sang a ‘I Want To Be Loved By You’ accompanied by piano and The D-Day Darlings performed ‘We’ll Meet Again’ by Vera Lynn.
Britain's Got Talent continues Saturday nights on ITV.