use Data::Dumper;

my @arr = (
    [ 0 .. 2 ],
    [ 3 .. 5 ],
    [ 6 .. 8 ],
);

print Data::Dumper->Dump( [\@arr] );

splice @{$arr[2]}, 1, 1;

print Data::Dumper->Dump( [\@arr] );

--------

$VAR1 = [
          [
            0,
            1,
            2
          ],
          [
            3,
            4,
            5
          ],
          [
            6,
            7,
            8
          ]
        ];
$VAR1 = [
          [
            0,
            1,
            2
          ],
          [
            3,
            4,
            5
          ],
          [
            6,
            8
          ]
        ];