Tenancy agreement misfiled and I'm not on it - does that mean I can leave at any time?

My flat is on a periodic tenancy and recently one of us left and a new person moved in. The homeowner changed property management companies a couple of years ago, and they apparently mishandled the transfer and lodged the previous version of the agreement. The person who I replaced is still on there and my variation on the agreement was somehow missed, so I'm not actually on the tenancy officially. They still have my bond on file though.

Lately I've been considering moving. Does the situation with the tenancy mean that I have no legal obligations to the flat? I mean, I won't just move out in the night with no notice or anything, I'm not cruel. I just want to know what my rights/obligations actually are in this situation.