In that case I suggest that you try the "expanded" version of the line - that will be much easier to diagnose. If you still have trouble try generating a code sample that demonstrates the problem without requiring the extranious code. Something like this:

#!/usr/bin/perl -w
use strict;

my $doc = {Result =>
          {first => 1, second => 2}
          #['first', 'second']
          };

my @list;

if (ref $doc->{Result} eq "HASH") {
     @list = keys %{$doc->{Result}};
} elsif (ref $doc->{Result} eq "ARRAY") {
     @list = @{$doc->{Result}};
} else {
     @list = ();
}

for (@list) {
     print "$_\n";
}
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which prints the following (without errors or warnings):

first
second
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You might also like to use Data::Dump::Streamer to dump the contents of $doc so that you can see what is causing grief in the data.