To start with, I'd use single quotes in you definition of $mydir so as to avoid escaping your slashes, make it easier to read, and provide a visual cue that no interpolation is going on here.

While I second that, ITYM backslashes, and sometimes they do need to be escaped in single quotes too; moreover prefixing a backslash with another one does escape it, yielding a single one:

$ perl -l
print for '\'foo', '\\\'foo', '\foo', '\\foo'
'foo
\'foo
\foo
\foo
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