If you don't fancy reading the excellent perlrun to find out what the flags do, then just use B::Deparse to find out:

$ perl -MO=Deparse -F'"' -lE 'say $F[$_ * 2 + 1] for 0 .. $#F/2'
BEGIN { $/ = "\n"; $\ = "\n"; }
use feature 'current_sub', 'bitwise', 'evalbytes', 'fc', 'postderef_qq
+', 'say', 'state', 'switch', 'unicode_strings', 'unicode_eval';
LINE: while (defined($_ = readline ARGV)) {
    chomp $_;
    our @F = split(/"/u, $_, 0);
    say $F[$_ * 2 + 1] foreach (0 .. $#F / 2);
}
-e syntax OK
[download]

(Updated to match the original code)

A dedicated module is better, but if you're shy of that, another approach:

c:\@Work\Perl\monks>perl

use strict;
use warnings;

my @lines = (
  '50 0 "R0 G255 B0 A255" "Solid" 118 1 "R0 G0 B0 A255" "R0 G0 B0 A255
+" 0',
  '70 0 "R0 G255 B255 A255" "Solid" 118 1 "R12 \"G12\" B12 A255" "R12 
+G12 B12 A255" 0',
  );

my $rx_dq = qr{ " [^"\\]* (?: \\. [^"\\]*)* " }xms;

for my $line (@lines) {
    my @d_quoted = $line =~ m{ $rx_dq }xmsg;
    print "@d_quoted \n";
    }

^Z
"R0 G255 B0 A255" "Solid" "R0 G0 B0 A255" "R0 G0 B0 A255"
"R0 G255 B255 A255" "Solid" "R12 \"G12\" B12 A255" "R12 G12 B12 A255"
[download]