Future Diary/Fridge

Fridge Brilliance

 * Way back in Chapter 1, when Yuno knows that Yuki might stab her with the dart, she seems totally indifferent about that, pins him against a wall, kisses him, and says "You didn't stab me.", as if she knew ahead of time he wouldn't, even though her Diary wouldn't be reliable against Yuki in a fight against him. Of course she would know...
 * Heck, a lot of Yuno's behavior can be explained keeping this in mind:
 * "How can she talk about killing someone so easily?"
 * Yuno suddenly deciding to meditate in Yukiteru's house to find the 5th's diary? She wasn't just trying to put herself in his shoes,
 * Yuno's surprise at Yukiteru's friends betraying him in Minene's attack on the school?
 * Her immediate suspicion of Tsubaki's motives?
 * The only reason why she probably couldn't use to her advantage is because
 * It should be noted that the above are rendered half-moot by the fact that
 * The ending makes complete sense if you just remember who they were going to replace.
 * Why did Mur Mur get hit by Akise bike,, and ask to be taken to a amusement park?
 * At the end of the first opening, and in several bits of the second feature Yuno going Ax Crazy with what appears to be another Yuno and then fusing with her. While at first glance this may look like your typical random Anime opening moment, it becomes a great form of foreshadowing when you consider future revelations about Yuno.
 * This might be a little coincidental, but the first opening and ending themes perfectly capture the essence of a yandere (especially considering that one of the main characters is the defining example) with the opening being crazy, hectic, creepy and psychotic, representing the "yan" part, while the ending is more calm, representing the "dere" part.

Fridge Horror

 * Everything seems fine in the end with . That is, until you start to wonder - ? And does that mean ? Not to mention this means that too...
 * Considering that Deus picks them as his successor, probably not. The whole point to the game was to find a successor, after all.
 * There is a panel with the 3rd-world 11th specifically telling Deus that he's canceling his plans for a "Future diary game." Also it's presumed that 3rd-world Deus came and found 2nd-world Yuki and 3rd-world Yuno to replace him before the 3rd world could end.
 * However it could also mean ...

Fridge Logic

 * In episodes 13/14 of the anime, the deathtrap meant to kill was changed from a room filling up with cement to a room filling up with gas. They manage to escape by . That gives me two questions, though. First, how is the gas supposed to fill the room if there's an air vent? And second, why would  use gas when the air vent in that room is also connected to the vent in her own room (which means )?
 * That depends on what kind of gas it is. Chlorine gas, for example, is heavier than air, so the gas would collect at the bottom of the room instead of diffusing through the air vent.