Over the last year or so, I've come across a few errors (mostly factual) that have been printed in comedy reference books and DVD sleeves.
Mark Lewisohn's Radio Times Guide to TV Comedy:
The comprehensive handbook that it is, I couldn't help but notice these:
Page 96 - entry for Birds of a Feather - states that Sharon was pregnant during series 8 and 9, rather than Tracey.
Page 311 - entry for Game On - Martin's surname is given as Henderson, rather than Henson.
Several DVD sleeve mistakes too - I'll have to add these later.