Before killing Tuvix, Tuvix speaks to everyone on the bridge, telling them they will have to live with it. And tada, no one has to live with it because the show completely forgot about the entire incident by the next episode.
The doctor becomes insane because of a moral conflict in his programming and has to deal with it instead of wiping his program. But even that is completely forgotten about.
Some crewmember that we have never seen before dies and returns and is supposed to be best friends with everyone. Yeah right.
Even that year of hell thing completely misfired. There was an episode where Kes aged backwards and at the end reported everyone about the Krenim and their temporal torpedoes. And then they meet the Krenim and nobody remembers.
Stuff like that annoyed me the most about Voyager. It barely has any continuity.
I prefer DS9.