In the film, Callahan's character is seen playing with a Rubick's Cube. The film takes place in 1974, but Rubick's Cube was not available in the markets until 1977 as a limited edition in Budapest only, known as the Magic Cube, and until 1980 internationally, when it was re-named "Rubick's Cube" after its inventor.
The turntable shown in the party scene is a Pioneer PL-518 which was not manufactured until 1978.