Episode 6 : Gontrand, a dog, is dead and it's a major plot point. During an explanation, we see the dog and see him "die" but he is clearly alive on the pictures (no blood or whatsoever)
Episode 2 : 30:04 - 30:08, Flashback, the main character as a kid is carsick and is talking to his father.
This scene is mentionned multiple times during the series.
Ep 2: A building is seen on fire and a little girl says "why are all my toys burning" however this is only in Kyan's imagination
Ep 6: a child loses his toy in a flashback but 30 years later he buys it back