What version of Acme::EyeDrops are you using? This sounds like perl RT bug #23143, namely:

The following program works under Perl 5.8.0 but fails under 5.8.1-RC2 with the error: "panic: pad_free curpad".

''=~m<(?{eval'print 4;$_=9'})>;($_)=9;
[download]

If you change it to:

''=~m<(?{eval'print 4;$_=9'})>;$_=9;
[download]

it works fine.

This perl bug was worked around in Acme::EyeDrops 1.42 and later, by never using $_ in filler code.