Broken Base: Some viewers like the slow burn pace of the work that eschews a more traditional and intense conflict-climax-resolution structure in favour of inviting the viewer to share in the emotions of the characters. Others find it boring for that exact same reason.
Fridge Logic: In the last third, Takaki and Akari cross the railway crossing just moments before two trains whiz past. Doesn't this world have the most basic of safety precautions?
Memetic Mutation: "Fuck trains", in reference to the very long time a pair of trains take to pass in the final scene, by the end of which Akari has already disappeared, preventing Takaki from reaching out to her.
Signature Scene: Takaki and maybe-Akari crossing paths at the railway crossing when they are adults and the subsequent vehicle vanish.