When Leonard Is talking with Doris, Just after she has exited the Cab and he has left the Phone-booth, he pokes fun at her for giving credence to the "Thin spots" and "Dimensions" that Archibald (the Cab driver) told her about. But Leonard was In the Phone booth making the call to his Boss while the whole discussion between Doris and Archibald took place In the Cab. Leonard Is talking about things he can't possibly have knowledge of.
Although mostly blurred, the car registrations shown are not British. The rear number plates in the UK are yellow with black figures. Here they have a white background.