and I don't know where the extra characters come from at the end of the output

You aren't using warnings, are you? :) You may have one or more extra newlines at the end of your data, which get inserted as empty arrays.

You may consider skipping empty lines:

# From ikegami's code
while (<DATA>) {
    chomp;
    push(@records, [ split(/\|/) ]) unless /^\s*$/;
}
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