I would change the \@release into \$release and use : colon or pipe separated values to send multiple arguments without repeating the option. Then simply create your array with a split.

use Getopt::Long;
our $realeases;
GetOptions(
    't=s' => \ our $target,
    'b=s' => \ our $buildtype,
    'r=s' => \ $releases
);

our @releases = split(/\:/,$releases);
[download]

Program is called with:

perl script.pl -r 1:2:3 -b blah -t blah
[download]