Just to say this Brit enjoyed your book immensely, even if my eyes glazed over the Roger Maris questions. It's ok to be on here, right? We're so over that tea party thing.
A few comments and possible corrections:
p53: Athough the statue in Piccadilly Circus is generally called "Eros" by tourists, it's actually a statue of his twin brother Anteros. As an aside, Piccadilly Circus is no longer a roundabout, but a controlled traffic junction that would test the patience of Sisyphus.
p54: Might be a UK/US thing, but "billiards" is a different game here using three balls (a white, a spotted white and a red ball). The yellow 1 ball is used in what we'd call (and you'd call) pool.
p74: Cucumber's a fruit, not a vegetable. It's the seeds, you see.
p96: It wasn't "odd" to leave the second best bed to the wife. This was common practice, as it was usual for the next generation to be given the best goods as they'd have the most use out of it.
p109: The square root of minus 1 is also written as j, especially if you're an engineer (they just have to be different, don't they?)
p155: Although Q doesn't appear in the Periodic Table of elements, isn't the same true of J also?
p183: Didn't Ugly Betty have its roots in Colombia, not Venezuela?
p204: My Filipino wife doubts that the Philippines has two capital cities. Quezon City used to be a capital but no more (since the 1970s or so). I may have misunderstood the answer, but I presume you're driving at places that have an official and administrative capital, right? As far as we can tell, Manila is the sole capital.
p286: Double typo in the name of Liz I's sneaky spymaster: he's actually Sir Francis Walsingham.
p290: Hitler did not really "write" Mein Kampf. He dictated it while in jail.
p295: The "was" in Qu6 is misleading as both the Athenaeum and Reform Club are alive and kicking, and still in Pall Mall.
p328: In the cricket diagram, I don't understand what the two small circles are around the batsmen unless they are some kind of safety feature (e.g. to stop fielders standing too close to the batsmen) that isn't used in UK and international cricket. Usually there is just the large oval for the fielders (e.g. during Powerplays) and the outside boundary.
p320: As far as I can tell, the Dvorak keyboard appears to be spelt without the accents that the composer has.
p331: As I live in his home town, I believe it's EADWEARD Muybridge who changed his name to that because one of the English kings who was crowned here had his name spelt like that on the Coronation Stone.
p452: For info, there is a long-running UK chat show called Room 101, which may have aired in the US on some godforsaken arm of the BBC. But probably not.
p472: To say that "IIII" on clocks is "non-standard" is a little unfair as that's how the Romans would have written it. "IV" is the non-standard way, really, as it was a later medieval invention.
Finally, p60's 2nd quiz instructions should read "...from the Queen's English into our mangled Hickspeak." I mean, "I'll write you Wednesday" - what's that all about?