The movie was funny in very few moments for me.
The science wasn't believable, but it was comedically unbelievable which was one of the few things I found funny. Still, a little more attempt would have been nice.
Every character had the same awkwardly quiet reserved personality quirk mixed with other repetitive quirks that were missing from one or two of the others. One character with that trait is believable maybe two to play off of one another but not everyone. Everyone having it though just constantly Yanks me out of the story.
Fourth wall breaks are only funny when Deadpool does them.
And the theme song is about the biblical afterlife, but the movie plays it in relation to zombies which makes it all the more annoying and boring.