Hi Anonymous Monk,
Just a reminder, that the array @array_rev has undef as it's first element, since array index start from "0". So, what you are doing with this @{$array_rev[1]}=(1,2,3); is to assign an array reference to the second element of the array @array_rev.
Using Data::Dumper like so can give some insight:

use Data::Dumper;

my @array_rev;
@{$array_rev[1]}=(1,2,3);
print Dumper \@array_rev;
__END__
$VAR1 = [
          undef,
          [
            1,
            2,
            3
          ]
        ];
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