The Checklist set is generally looking good.

I noticed when I was logged in as a guest that the Checklist block still shows with some content.

I suggest that guests should not see the block content at all (easy to set the block content to noghting), which will hide the block. Alternately a prompt suggesting the user logs in could be shown, but that would be incosistent with other block behaviour.

I also noticed that when you click on the bar in the Checklist block that it takes you to the activity (as does clicking the activity link). When viewing the activity, an error is shown.

get_referer() is deprecated. Please use get_local_referer() instead.

line 2372 of /lib/deprecatedlib.php: call to debugging()

line 533 of /mod/checklist/locallib.php: call to get_referer()

line 65 of /mod/checklist/view.php: call to checklist_class->view()

That seems unrelated, but something I thought you might want to know about.