Array of Arrays in Perl

The following code snippet provides the often-saught Array of Arrays in Perl. This is my take on the Array of Arrays exercise from the book of Intermediate Perl, also known as the Alpaca book.

sub check_required_items {

 my $who = shift;
 my $items = shift;

 my %whose_items = map { $_, 1 } @$items;

 my @required = qw(preserver sunscreen water_bottle jacket);
 my @missing = ( );

 for my $item (@required) {
 unless ($whose_items{$item}) {
 print "$who is missing $item.\n";
 push @missing, $item;
 }
 }

 if(@missing) {
 print "Adding @missing to @$items for $who.\n";
 push @$items, @missing;
 }
}

sub check_items_for_all {
 my $all_with_names_ref = shift;
 foreach my $person (keys %$all_with_names_ref) { 
 check_required_items($person,\@{$$all_with_names_ref{$person}});
 }
}

my @gilligan = qw(red_shirt hat lucky_socks water_bottle);
my @skipper = qw(blue_shirt hat jacket preserver sunscreen);
my @professor = qw(sunscreen water_bottle slide_rule batteries radio);

my %all = ( 
 Gilligan => \@gilligan,
 Skipper => \@skipper,
 Professor => \@professor, 
);

check_items_for_all(\%all);