As long as you don't need to initialise the array, you should be fine if you simply omit the parentheses. For example

#!/usr/bin/perl

use Getopt::Long;
GetOptions(
    'thing=s' => \(my $thing = ''),
    'flag'    => \(my $flag = 0),
    'array=s' => \my @array,        # no parens
    # ...
) or die 'options';

print "\@array: @array\n";
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when called as

$ ./646480.pl -a foo -a bar -a baz
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would print as expected

@array: foo bar baz
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