"Strange Days" features a mixture of psychedelia, acid rock and psychedelic rock; the band also explored musique concrète techniques on the album. During the recording of "Unhappy Girl", keyboardist Ray Manzarek played his keyboard introduction backwards, and the corresponding overdubs were later made. Manzarek also contributed marimba on some of the album's tracks. The title track "Strange Days" is described as "one of the earliest examples of the Moog synthesizer in rock". The synth was hooked up with the help of Paul Beaver and played by Morrison.