A few things

[Prayer]

Poison spiders don't even poison you. Anti-poison is like worthless if you don't add that



This Fisherman in lumbridge shouldn't even be there o.o



Giant spiders don't contribute to a spider task, only small spiders do.



After completing the Halloween event most replaced object ids go invisible.





With just a relog it shows that you're standing on top of a bush that was supposed to be there.

[Dev Sean]

Most of these have been fixed. However I've filed an issue for the spider-related bugs.

Reference:
blitz/core-engine/issues/#70
blitz/slayer/issues/#6

- Dev Sean