Just to demonstrate the effect of dynamic scoping that AnomalousMonk already described:

sub foo {
    local *bar = sub {
        print "other bar\n";
    };
    print "foo calling quz\n";
    quz();
}
sub bar {
    print "bar\n";
}
sub quz {
    print "quz calling bar\n";
    bar();
}
foo();
quz();
__END__
Subroutine main::bar redefined at - line 4.
foo calling quz
quz calling bar
other bar
quz calling bar
bar
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Despite the warning about the subroutine being redefined, this can cause some spooky action-at-a-distance effects: How do you know which bar() you'll be calling (as demonstrated by sub quz)?