Code-switching and -mixing have been prominent in Hong Kongers’ speech patterns. Yet, cinematic representations of these two practices seem to be rare in studio-produced films and have only emerged in experimental and independent films since the 1990s. In this article, I argue that the discrepancy between the commonplaceness of code-switching and -mixing in Hong Kongers’ everyday speech and its lack of representation in the cinema is deceptive. If we understand code-switching and -mixing not only as an interlinguistic practice, but also as intertopolectic (between different topolects) and intratopolectic (between registers of a topolect of language), code-switching and -mixing have always been part of Hong Kong cinema as narrational devices. Moreover, in some cinematic cases, code-switching and -mixing may be transposed to the level of film forms. In this article, I will first provide an overview of how code-switching and -mixing in Hong Kong have been discussed by linguists and point out some blind spots in their arguments. I will then conduct a comparative investigation into Cantonese literature and classical Cantonese cinema from the 1930s to the 1950s and demonstrate how interlinguistic, intertopolectic, and intratopolectic switching and mixing have always been part of it. I will then conduct a similar investigation into Cold War Mandarin literature in Hong Kong and its use of code-switching and -mixing, which will shed light on how Mandarin cinema in the 1950s transposes these practices to film forms. In both cases, code-switching and -mixing in the cinema negotiate the conflicting social relationships of the time.