It seems to miss cases like:

  $foo ->[2];                  # Space before or after ->
  print $_->{bar};             # Only two non-space chars before ->
  $sum += $_->[0] for @array;  # Only three non-space chars after ->
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And since you aren't using warnings, you don't get a warning if you try to print an undefined $1.

OTOH, it would find a deref in:

  perl -ne '/(\S{3,80}->\S{5,80})/;print $1,"\n"'
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Don't tell me you never write code like that!

But I'm baffled by the fact you're searching for '->' when you need to figure out which hashes are in some code.