But no matter what kind of casts and !@#$%^&* stuff I put in there (like $# @{ $thirdList{$area} }, I get a "$# is no longer supported" type of error

Sometimes, you need squigglies.

Alternately,

while (my ($area, $list) = each %thirdList) {
   foreach my $item (@$list) {
      print join(' - ', @$item), "\n";
   }
}
[download]