The car that Johnny English used was an Aston Martin DB7 Vantage, which was actually Rowan Atkinson's own car.
The first scene showing Johnny English in his office, just after the dream introductory sequence, Rowan Atkinson is wearing the classic "Mr. Bean" outfit.
In the Sushi Bar scene, when Johnny English (Rowan Atkinson) and Agent Lorna Campbell (Natalie Imbruglia) were toasting, Johnny said a sentence in Japanese which subtitled into English as "May all your daughters be born with three bottoms." What he actually said in Japanese was "Kimi no musumesan-tachi ni chiisai chinchin ga tsuitemasu you ni", which literally means "May all your daughters have small penises." Coincidentally, in The Tall Guy (1989), Jeff Goldblum's character yells at Atkinson, "I hope all your children have very small d***s! And that includes the girls!"
The Johnny English character is based on a cowardly, incompetent spy played by Rowan Atkinson who first appeared in a series of television commercials for Barclaycard, with his assistant Bough (then played by Henry Naylor). The "poison dart pen" sequence is based on a scene in the commercials where Johnny shoots himself in the leg with the pen.
Two of the screenwriters (Neal Purvis and Robert Wade) also worked on seven James Bond movies: The World Is Not Enough (1999), Die Another Day (2002), Casino Royale (2006), Quantum of Solace (2008), Skyfall (2012), Spectre (2015), and No Time to Die (2021).