Paul and Linda marry in a "Registry Office" according to the sign above the door and the news reporter's voiceover. It is actually called a Register Office - there is not such thing as a "Registry Office".
None of the "British" cars have U.K. Road Fund Licence discs ("Tax Discs") in the windscreen.
When Linda first arrives at Paul's London home the loud sound of cicadas is heard outside. The London night does not sound like this.
During a phone conversation there are two voices saying roughly the same lines, obviously one is the script prompter feeding the lines to the person on the phone.