An example:

my %hash;
$hash{beta} = 'x';
for my $name ( qw(alpha beta) ) {
    push @{$hash{$name}}, 123, 456;
}

use Data::Dumper;
print Dumper \%hash;
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$VAR1 = {
          'alpha' => [
                       123,
                       456
                     ],
          'beta' => 'x'
        };
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print Dumper \@x;
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$VAR1 = [
          123,
          456
        ];
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With strict enabled, it'll get caught while trying to push the data: insert the line

use strict;
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Can't use string ("x") as an ARRAY ref while "strict refs" in use at t
+est.pl line 6.
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Nasty if you didn't expect it.

The risk of running into it is greatest when using data structures of unequal depth.