The short centers around two vaguely Casper-ish creatures, the personifications of Day and Night. The two characters are set against a featureless black background, but they themselves are windows into two scenes, a day scene with a sun in the sky inside Day, and a night scene with a moon in the sky inside Night. The scenes shown inside them usually correspond to their actions; for example, when Day is waking up in the morning, we see a morning scene with the sun rising on a farm, and when Night is sleeping, we see sheep jumping a fence in the stereotypical "counting sheep" scene.
Day is startled to run into Night, who is sleeping. It soon becomes clear that the views we see inside of them are of the exact same place, but a daytime shot inside Day and a nighttime shot inside Night. The two take an instant dislike to each other, and soon they get into a fight. They eventually find out, however, that they do better working together.
Played in theaters in front of Pixar feature Toy Story 3.
- Always Night: Inside Night, and Endless Daytime inside Day. This causes some frustrations. Night sees the sexy bikini-clad woman sunbathing on the beach inside Day. He wants to join the sexy girl, but when he pushes Day out of the way and jumps to that same spot, we see the night scene inside of him, and the beach is empty.
- An Aesop: "Different" doesn't necessarily mean "bad." This is lampshaded when they find a radio station, which, when Day is in front of it, transmits a broadcast. The broadcast turns out to be a stock recording of a lecture by philosopher Dr. Wayne Dyer.Wayne Dyer: Fear of the unknown...They are afraid of new ideas...They are loaded with prejudices, not based upon anything in reality, but based on..."If something is new, I reject it immediately because it's frightening to me." What they do instead is just stay with the familiar. You know, to me, the most beautiful things in all the universe, are the most mysterious.
- Anthropomorphic Personification: Personifications of the concepts of Day and Night.
- Art Shift: Combines 2D and 3D animation.
- The Cameo: Construction Worker Tom and Alpha from Up make brief cameoes in this short.
- Circling Birdies: We see a flock of birds flying around inside Day after Night punches him in the jaw.
- Counting Sheep: What goes on inside Night as he sleeps.
- Close on Title: The title doesn't pop up until the end.
- Dark Is Not Evil: Night, but it's actually more of "Dark is not a freak".
- Does This Remind You of Anything?: Day wakes up, with a scene of daybreak inside him. He yawns, stretches, and shuffles off as the camera "inside" him pans across a farm morning scene. Then he stops at a waterfall...and sighs with relief. The waterfall symbolizes urinating.
- Endless Daytime: See Always Night above.
- Fake-Out Opening: The film opens with a Down on the Farm scene, rooster crowing at daybreak. Then the camera pulls back and things get weirder as we find out that the farm scene is actually contained within the creature Day.
- Medium Blending: Traditional-looking 2D for the drawings of Day and Night, 3D for the action that takes place inside them.
- Mind Screw: Day & Night is a feast for the eyes. But if you try to make sense of it...
- Name and Name: Day and Night
- Night and Day Duo: Day and Night are Anthropomorphic Personifications of day and night, respectively, as humanoid figures who have daytime and nighttime versions of the same scenes visible through their bodies. At first they are at odds with each other, but then they find common ground and become friends, and in the end they switch places as the sun sets on one and rises on the other.
- Not So Different: The ending for Day and Night, in which the rising and setting of the Sun turns each into the other.
- Painting the Medium: Day & Night basically changes the medium into a pair of characters representing...well, you know.
- Stock Scream: The Wilhelm Scream is heard as Night shows Day a movie at a drive-in theater.
- Unmoving Plaid: An invoked variation. Day and Night are basically windows to the scene behind them, and we see the same thing if either of them are standing in a particular place, with the only difference being that one is a day scene and one is a night scene. For example, when Day stands in front of a beach, we see the beach in day with a woman sunbathing and a lighthouse turned off behind her. When Night stands in front of the same spot it's the beach at night, with the woman gone and the lighthouse beaming its light out into the ocean.
- Visual Pun: Chock full of them, which helps represent the characters' mood and actions. At one point, Night punches Day in the jaw; as Day falls over, we see within him a scene of a lumberjack chopping down a tree.
- Viva Las Vegas!: We see a scene of the Las Vegas Strip inside Day. Night then pulls Day out of the way and takes his place, and we then see the Strip at night, when it's lit up and a lot more impressive.
- Volumetric Mouth: At the start, Day gets one while yawning awake (and mooing like a cow while doing so).