The film was not originally intended to be a period piece. As the crew was location scouting, one of the houses they found was filled with furniture and appliances from the 50s and 60s, and so it became cheaper to set the year in the film to 1965.
The heel to Ken's right shoe broke at some point over production, and it visibly separates from the shoe for the second half of the film.
The car used in the film is a 1965 Chevy Corvair. Although it looks as if Ken is working out of his trunk in the beginning of the film, the engine to that car model was actually located in the back of the car.
Rebecca's house is actually two separate houses located directly next to each other. The house used for exteriors was previously owned by a hoarder and was filled with old, dirty appliances from the 60s. The house used for interiors was not aesthetically pleasing on the outside, so the crew made the best of both worlds.
The opening and closing song, "Out of the Gray," was actually written by a teacher that the director, Dan Helbling, had in high school.