use Data::Dumper;

foreach (qw/ one two three /) {
   $hash{$_}  = "in hash: $_";
   $array[$_] = "in array: $_";
}

print Dumper(\%hash, \@array);

$VAR1 = {
          'one'   => 'in hash: one',
          'three' => 'in hash: three',
          'two'   => 'in hash: two'
        };
$VAR2 = [
          'in array: three'
        ];
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The string in the array assignment is being interpreted in a numeric context, which makes it 0. Thus you are getting data from and assigning to index 0 of the array every time. The hash will grow, while the array will only contain the last item you save.