24 things you didn't know about 24
1 Jack Bauer has killed 112 people over the five years of the show. Season 4, during which he dispatched 44 'hostiles', was his best ever; in the first season he managed a lacklustre 10.
2 Kiefer Sutherland heard that American college students use 24 as a drinking game, downing a shot every time Jack Bauer says 'damn it'. So he changed the script in one episode to have Jack say 'damn it' 14 times in one hour.
3 Another frat-house game is to monitor Jack's flouting of the Geneva Conventions. In season 2 he shot a key suspect under interrogation in the heart before beheading him. In season 3, he executed a colleague on the president's orders.
4 Jack's entry codes for CTU (Counter Terrorism Unit) are 4393 and Q22Q17
5 For season 2, a prototype script was written in which each (non real-time) episode would span 24 hours, but execs decided to stick to the original format.
6 During season 4 an incoming call number was shown on a character's mobile phone. More than 50,000 fans dialled the number - only to find it was real and belonged to one of the crew.
7 More than 20 lead characters have died in seasons 1-5.
8 Jack Bauer has actually died twice. In season 2 he was tortured, burned and tazered to death before miraculously coming round. In season 4 he was shot dead; then Tony Almeida injected him with epinephrine and he recovered.
9 Executive Producer Evan Katz once said: 'We make a lot of it up as we go along.'
10 24 was the first TV show to embrace real-time - the clock keeps ticking during ad breaks and there are no flashbacks.
11 Of course, it's not quite as simple as that. Three minutes are in fact gradually added to the timer during the ad breaks.
12 Almost all scenes are shot at head height.
13 We've never seen Jack eating, sleeping or going to the toilet. As a joke for season 5 he was filmed exiting the bathroom, eating a sandwich and wearing his pyjamas. It didn't make the final cut.
14 What might have been: 'The original iteration of 24 was that we were going to do 24 hours in the life of a wedding ... kind of a romantic comedy series.' (Creator Joel Surnow)
15 In the US, the Fox network had to screen adverts during season 4 episodes showing 'positive' images of Muslims, to counter charges of Islamophobia.
16 Everyone on the programme has to sign pledges not to reveal the plot.
17 Former presidential candidate and Republican Senator John McCain is such a fan of 24 he landed himself a walk-on part.
18 Blooper alert! The Californian presidential primary - the backdrop to season 1 - is held in March, not June.
19 The premiere was due to air in the US just one month after 9/11. Following the attacks, a shot of a 747 exploding was removed and the screening was delayed.
20 Jack's daughter, Kim, has been held captive in one form or other eight times.
21 Sarah Clarke was cast as Nina Myers on the morning filming was due to begin for the pilot episode.
22 Glenn Morshower, Kiefer Sutherland, Carlos Bernard and Dennis Haysbert are the only actors to appear in all five seasons.
23 To speak fluent Jack, use the following phrases often: 'Where's Kim?', 'Who are you working for?', 'Get down on the ground!' and, of course, 'Damn it!'
24 Fox commissioned two more series of 24 in May. A feature film will begin production next year, with parts to be shot in London.