And you think they pick up the "extra" information in fillers in later arcs? No. They will never be mentioned again ever.
Thats also general consensus. However I just said that fillers
sometimes and I really mean
only sometimes contains interesting additional stuff, even though some underpaid-scriptwriter sucked it out of his fingernails just for this one Ep. It's just not possible that it has any connection to the "real" series.
TL,DR: All I want to say is: If a filler was well made (thought out), it
can be enjoyable, though that's rarely the case. ┐( ̄ー ̄)┌
It is general consensus that fillers are useless otherwise the anime producers would never have started adapting long running shows. They would have use the idea of the manga series and created their own universe which is then only loosely based on the original script.
Happens here and there, mostly the outcome is pretty bad though.
[Edit: @ havoc: oops, used the word "general consensus" again. Couldn't resist.

. Can't remember seeing such a
series though.]