Corrected entry: At the start of the scene where Blu is picked up by Linda, a small bird is shown standing in front of a red traffic light, with the truck containing Blu travelling towards the bird's side. But when the driver brakes, the red light is now towards the truck, with no transition to that side.
Corrected entry: Blu is drinking hot cocoa. But the point is that hot cocoa is poisonous for birds.
Correction: Pure cocoa is toxic to most animals in sufficient doses, this is true. But there's nothing saying that the cocoa in Bu's cup is real cocoa or, if it is, undiluted enough to kill him. There's simply not enough information given in the movie to call this a mistake. Blu thinks it's cocoa, that's all we're told.
Correction: It could actually be cacao, which is a "chocolate" safe for animals like dogs. Look it up.
Correction: I thought the same thing at first but re-watching it, you can see the bird switch red lights like it did in the establishing shot.