Several bugs to do with teh Daily Ratings in the game.
One is that occasionally the game somehow entirely skips the end-of-week reward. This is frustrating to anyone who has worked their way through the entire week with their dwellers.
Second, and very vexing, is a bug where the game occasionally derps out on the happiness rating for a day and gives you an undeserved F RATING. I've had it happen when the game bugged out and didn't close itself properly- but all my resources are at max, my dwellers happiness is at 93%, but I open up the game to see a daily rating plummet to F? One of my close friends who also plays the game had the same issue, with full resources and a happiness in the 90s, suddenly got an F-rating for no apparent reason. Please fix this.
Another bug i've encountered is occasionally the phone goes into "sleep/screensaver" mode while playing, the game won't do it's timeout thing where your dwellers stop consuming resources, and instead they'll continue to consume resources the entire time, which can cause you to come back to a vault of dying, irradiated dwellers.
As well, often shortly after having a couple make a baby in one of the living areas, one (or more) of the pregnant female dwellers becomes completely un-selectable unless you restart the game- can't drag her anywhere.