I've managed to run your example script on both the latest rakudo built from git, plus rakudo star 2010.07.
I do notice however, that as soon as I put a blank line anywhere in the input file, I get the same error message as you:
Beth Ana Charlie Dave
Ana vs Dave | 3:0
Charlie vs Beth | 3:1
Ana vs Beth | 2:3
Dave vs Charlie | 3:0
Ana vs Charlie | 3:1
Beth vs Dave | 0:3
snoopy@snoopy-laptop:~/git/rakudo$ ./perl6 /tmp/score.p6
Method 'split' not found for invocant of class ''
in <anon> at line 12:/tmp/score.p6
in main program body at line 1
So I think it's got something to do with the input data or the line separators. Maybe the cut-and-paste introduced something?