I watched the sound version and the silent version ages ago and enjoyed them both. I preferred Anny Ondra when she was silent because the dubbing is all wrong. Joan Barry was far too posh. The knife scene works well both ways but I have to say the sound version is very clever. Hitchcock has turned into Hitchcock.
I love the glimpses of London in the twenties we get particularly those seen during Alice's walk of misery after the murder.
Appearance by a cat or dog: none
Transport: motor vehicles
Source: The Early Hitchcock Collection (Optimum Releasing)/Erpressung (Arthaus)