That's because you're actually creating references to references to arrays with my @array1 = [1..5];...
try :

 ($r_array1, $r_array2) = foo();
  print "@$r_array1\n";
  print "@$r_array2\n";

  sub foo {
      my @array1 = (1..5);
      my @array2 = (6..10);
      return (\@array1, \@array2);
  }
[download]

Update: while we're recommending books on the subject... Damian Conway's Object Orientated Perl is really one of my favorites...

Greetz
Beatnik
... Quidquid perl dictum sit, altum viditur.