I've recently seen a poster for a rave (or whatever they're called
nowadays) on "Easter Thursday, 5th April". Actually, the 5th is
*Maundy* Thursday -- *Easter* Thursday is the 12th!

I've also seen a poster (from a greetings-card manufacturer) claiming
that Easter is the 9th April. Impossible, since the 9th is a Monday
but Easter, by definition, is always a Sunday.

Still, at least those ignoramuses who always call the second Bank
Holiday in May "Whitsun" are this year right for once -- said day is
indeed Pentecost Monday (to give it its formal name), although usually
it isn't...