Bernard enters the MAMBA BURGER fast food outlet. The pavement is wet but there is no rain. On the pavement, Bernard's footfall is silent. He walks into the fast food outlet where his footfall sounds very wet. The camera (from behind the counter) shows that outside it is not yet raining. Even when Bernard walks from the counter to the door. However, when he arrives at the door (2 camera shots from outside) there is heavy rain. Additionally, on the next camera shot (inside the fast food outlet) we can clearly see exceptionally heavy rain on the door and windows.
Bernard 'phones the shop to speak to Manny. We see the 'phone in the shop has its handset cable cut. In the 'phone kiosk Bernard hears the 'unobtainable' tone. That would happen only if the 'phone line to the shop was dis-connected, not because the handset was dis-connected.
The safety door installed on the Book Shop is soundproof. It's impossible to listen to Bernard's voice, but it's possible to hear cars passing and street noises from inside. If the street noises were heard perhaps from the windows, Bernard's voice should be heard at some volume as well.