&{$sub_i_want_to_call};

You probably want that to be &{$sub_i_want_to_call}(); (or the equivalent $sub_i_want_to_call->()). Subroutine calls with & but without parens give the callee direct access to the caller's @_, including the ability to modify it:

$ perl -w
sub foo { my $foo = shift }
sub bar { &foo; warn @_ }
bar("baz","quux","\n");
__END__
quux
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