Reddit reviews Perl Best Practices: Standards and Styles for Developing Maintainable Code

Using foreach over an array index would generally be considered non-idiomatic or "not very Perly". Sometimes you really need that index though. At least you didn't do a C-style for (my $i = 0;....

Using the references directly should be faster in theory. In reality, probably doesn't matter much.

EDIT: BTW, following the style of your co-worker has merit too. If you want to learn more about Perl style, checkout Damian Conway's Perl Best Practices.

Other languages encourage and practice code reuse and sharing of best practices a lot more than PHP. Consider for example: Perl Best Practices or Python PEPs.