use warnings;
use strict;
use Data::Dumper;

my @array;
my %hash = ( abc=>123 );
push @array, \%hash;
%hash = ( def=>456 );
push @array, \%hash;

print Dumper(\@array);
print $array[1]{def}, "\n"; # ok
print $array[0]{abc}, "\n"; # nope! hash was cleared!

__END__

$VAR1 = [
          {
            'def' => 456
          },
          $VAR1->[0]
        ];
456
Use of uninitialized value in print at test.pl line 13.