Today I ran into a little oddness with hash slices and using qw (grinder wrote an article on other issues here). It comes down to which quoting symbol you use: 
use strict;
use warnings;

my %hash=(a=>1,b=>2,c=>4,d=>8);
local $,="\t";
local $\="\n";

print @hash{qw'a b c d'}; # This throws a warning!
print @hash{qw(a b c d)}; # This doesnt!

__END__
Scalar value @hash{qw'a b c d'} better written 
  as $hash{qw'a b c d'} at D:\temp\hashbug.pl line 8.
1    2    4    8
1    2    4    8

[download]
So if you ever run into this warning then just change the quoting character for qw and the error message goes away.

But still if theres a logical reason for this Id love to hear it.

UPDATE:
To make it even weirder it seems that when you use the following notation you dont get warnings 

$ref=\%hash; 
print @{$ref}{qw'a b c'};

[download]

Yves / DeMerphq
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In reply to Bug with qw in hash slice. by demerphq

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