Looks like Communities breaks several of the G+ enhancement Chrome extensions. Or perhaps that's the other way round, the extensions break the community code. Extended Embed, G+me for Google Plus, GExtend all causing me problems.
Same here, I cannot see the "Add a comment" field in Chrome while it's fine in IE. Many extensions will need to be updated to work with Communities. It's probably just a matter of days until most of them will work again...