in reply to Re^2: regexp list return 5.6 vs 5.8
in thread regexp list return 5.6 vs 5.8

You're right about the behavior of slices, but it has nothing to do with subroutine returns. See for example:
perl -e"my @a=qw/a b c/; print scalar @a[0..2]" c
The issue is that an array (or hash, or list) slice in scalar context returns the last element of the slice. I feel like this should be documented in perldata but a quick read of it just now didn't reveal any such indication.