BEGIN { $^W = 1; }
use IO::Socket;
use strict 'refs';
local $/ = "\r\n";
my $port = '7070';
my $root = '/home/beth/gopher/gopher';
die "can't chroot: $!\n" unless chroot $root;
local $SIG{'HUP'} = 'IGNORE';
exit if my $pid = fork;
die "Couldn't create socket: $!\n" unless my $sock = 'IO::Socket::INET
+'->new('LocalPort', $port, 'Type', SOCK_STREAM(), 'Listen', 1, 'Reuse
+', 1);
my $s = $sock->accept;
while (defined(my $req = <$s>)) {
    chomp(my $req = shift @ARGV);
    $req = '/' . $req;
    &error unless -r $req;
    $req .= '/.cache' if -d _;
    printfile($req);
    close $sock;
}
sub printfile {
    use strict 'refs';
    open FILE, shift @_;
    binmode FILE;
    print $s <FILE>;
    close FILE;
}
sub error {
    use strict 'refs';
    my $req = shift @_;
    print $s "iBad Request: $! \tfake\t(NULL)\t0" . $/;
}
[download]

Please note the following: (line#'s from your code)

1. Lines 31 and 33 both assign to my $req. On 33, it's assigning to shift @ARGV.
2. You assign $req to shift on line 51, but don't use it and don't pass anything in to error(), either.
3. You don't use $pid from line 17. So, essentially, you're forking to create a child, then exiting the child immediately ... ?
4. Unless I'm mistaken, you'll only ever serve one request for one client, then leave ... ?

I'm not trying to rip it apart, but I couldn't understand it to golf it. :-(