There were two things in the finale that made no sense to the group I was watching with.
Other than prolonging the story for drama, why did Al not immediately fire on Martha with a harnessed Jim zombie? She knows Martha's M.O., so it made no sense for Al to have a conversation with a zombie in her face.
When Strand had trouble getting the valve on the ethanol tanker, I thought Al came up with a great dual-purpose solution with her SWAT van guns - taking out all the walkers and open the tanker at the same time. The most ridiculous revelation from the other characters followed when they informed Morgan that they had lost all the ethanol. How did not one character think to catch the ethanol pouring from the bullet holes in the gas can that they brought out for that purpose?
This was my favorite season of this show largely because of the new cast, but it still has some bad writing moments.