Tuck is able to speak to Jack from anywhere in Jack's body - that's up to a good four-five feet from the receiver in Jack's ear. So how come Tuck can't pick up from or send to the receiver when he's in Lydia, but still within four feet?
For that matter, why was Tuck in Jack's mouth for the kiss?
Why did Jack's doctor, co-worker and boss get invited to Tuck and Lydia's wedding?
Probably because in the interim, they became Tuck and Lydia's friends too?
So Tuck's vessel caught champagne that Jack drank from inside and he drank it, isn't that a little nasty and anti-hygienic? It contained Jack's saliva and bacterias!