Thanks. That reminded of one thing I had been trying to remember to include:

 $ perl -e'print qr/C$\n^D/,$/'
(?-xism:Cn^D)
 $ perl -le'print qr/C$\n^D/'
(?-xism:C
n^D)
[download]

which is a lower-tech way to notice that your regex wasn't parsed the way you expected. (It also demonstrates why I use -l: so I don't have a append newlines to each of my print statements.)