Turning on strict and warnings helps a boodle.

Converting your code to

#!/usr/bin/perl

use strict;
use warnings;

my @temp = (2,3,4);
my @selects;
$selects[0] = [@temp];
my $refdates = $selects[0];
#my @workdts = @$refdates;
my @workdts = @$selects[0];

print "$_\n" for @workdts;
[download]

gives me

Global symbol "$selects" requires explicit package name at ./p line...
[download]

Now since we explicitly declared @selects as an array, then $selects[0] should be an array element, which it is, and we only need to cast that reference to an array type.

Well, since @ binds tighter than subscripting, the compiler thought we were trying to use @$selects, which implies that $selects, the scalar, exists. Since it doesn't, we need to enforce what we want with braces.

@{$selects[0]}
[download]

This will give us the result we desire.

Hope this helped,
-v.