Funniest and strangest ever blooper for me is at the very end of FRWL - it makes me grin every time - and I first noticed this years ago when I had the soundtrack on a compilation. I thought someone had just screwed up the recording when they made the compilation but then I heard this again too much more recently when FRWL was on the telly!
Listen very carefully to the title song until he gets to the line "but oh.... ...you haunted me so". During that pause between "oh" and "you" is a quiet but strange and very funny sound like someone talking but sped up very fast!

I don't know why but I just find it hilarious as I can't possibly imagine how it got there and it's so weird they didn't edit it out - and even weirder that no-one else online ever seems to have mentioned it!
I told a colleague about it years ago and he claimed to also have noticed it. Anyone here heard it too?