Well done! No, you didn't post too quickly and you gain kudos for posting a follow up with the stuff you found and figured out. Once again: well done!

The perlsub (I recommend the more up to date perldoc.org link btw) is indeed the place to go for the god oil on this matter, although some of the subtle traps are not really highlighted.

As you found calling using & ignores prototypes. However as prototypes should almost never be used that is not a big issue. The more subtle potential trap is that the current contents of @_ is used as the argument list to the called subroutine if no explicit arguments are provided.