When Jerry (Jerry Seinfeld) and George (Jason Alexander) are walking down the stairway talking about Red China, they are walking side by side. In the next shot after they round the corner, they have switched places.
A replica garage was built in the studio and they used mirrors to make it look bigger. In several scenes you can see various actors' reflections as they pass by, starting with Jerry, Elaine, George, and Kramer in the first scene.
The "Fragile" sticker was strategically placed over the name on the box to hide the real name of the air conditioner manufacturer Friedrich.
There are same cars in all scenes at parking. For example, dark blue Volvo 940, parked in different positions, is visible in many shots.
The car was parked in a handicapped space.
In the final scene, when Kramer (Michael Richards) gets out of the car & looks into the distance was completely improvised, and it's possible to see the other actors starting to laugh at the end of the take.
When Kramer nearly drops the AC box he sets it briefly on the hood of a red convertible parked next to a pillar that is painted green with no number on it, but directly across from "Green 11". Shortly after, when Kramer says that he thought he had parked at "Green 22" they are all standing right near "Green 20".
When the car is finally found at the end of the episode, "Green 20" is very clearly visible. The car is in the parking spot adjacent to where the red convertible was earlier in the episode, though now the pillar is marked "Green 12", and the letter "C" has been painted on the wall near the "Green 11" from earlier in the episode.