Actor Allusion: Sometimes with a few of the lies written for the guests, such as Neil Morrissey claiming to have had an extension on his house made by a builder named Bob, or Ronnie Corbett claiming to have asked for four candles in a hardware store.
Defictionalization: Omid Djalili's lie in Series 3 was that he was launching his own range of condiments, including Omid Djalili Picalili. The idea received such an enthusiastic response both on the programme and on Twitter that he later noted on his Twitter that he was seriously looking into getting some Djalili Picalili produced.
Deleted Scene: The compilation shows at the end of the series show a few turns that got cut out of the regular programmes. Clearly a lot of stuff gets taken out when editing the show down to 30 minutes, as the series 4 compilation show consists entirely of deleted scenes with no "best bits", and there's even more after that that never gets shown.
The series recording Spring 2014 takes about 3 hours per show - approximately 1 hour per round. In the first and third rounds more questions are asked than will get shown, so to give options to which is the funniest and clean enough for broadcast.
Enforced Method Acting: The panellists have never seen what is on the card before they read from it - all of the lies must have their details made up on the spot.note In the case of the truths, the panellists have a meeting with the producers before the show and write down a couple of truths so they can generally expect what might show up there.
Missing Episode: Series 2 episode 5 features a "Ring of Truth" question about Rolf Harris (introduced by a clip of Harris on Top of the Pops), and is unlikely to be broadcast in its original form again in light of Harris' conviction for child sex offences in June 2014.
Old Shame: Nick Hewer regrets his appearance in this programme, and claims he has never felt more embarrassed. Of course, his attempts to maintain his trademark sternness led a masterfully Comically Serious performance.
Promoted Fanboy: Rob, Lee, and David, despite being successful comedians/comic actors in their own right, geek out quite shamelessly in the presence of a longer-established figure.
One of Michael Aspel's "true" facts, shown in the series 2 Clip Show, was that he had received fanmail from then-host Angus Deayton.
Screwed by the Network: The show has not been scheduled consistently for two series running. Just when it looked like things might be improving with series 5, the BBC inexplicably decided to dump series 6 in an awful pre-watershed timeslot in the Spring with no promotion. (To add insult to injury, the last episode went missing for a month due to Euro 2012 and a filler documentary about the Queen's jubilee.)
The BBC refused to broadcast the 2017 series, for no reason whatsoever. They showed repeats in its place. It eventually turned up on Monday nights at the last possible moment (suggesting they actually had forgotten about it), whilst they continued to show sitcom repeats on the Friday.
Alan Carr was originally going to be a team captain instead of Lee Mack.
Roger Moore was announced as a guest on series 9, but did not appear at any of the recordings.
In an example that expands beyond the series, a "This is My" guest from Series 8 was John Duff Lowe, pianist for the Quarrymen for two years, including their first recording session (the tapes of which he kept until 1981, when Paul McCartney bought them for £12000; they were later re-mastered and included on Volume 1 of The Beatles Anthology). As Brookside alumnus Ricky Tomlinson told the Would I Lie to You? panel, Lowe left the Quarrymen before they became the Beatles to join Tomlinson's own band, the City Slickers.
The buttons the panellists press to (supposedly) bring the 'TRUTH/LIE' graphics up on screen aren't actually connected to anything and are purely for effect (as shown in a few out-takes where the panellists forget to push the button but the graphics come up anyway, or they do press the buttons but nothing happens).
In Series 11 Episode 8, David Mitchell says (as part of a claim) that in a Series 1 episode he claimed to only have one album (the full, true story being that in the ten years since he's only brought one more). The original claim was never broadcast.