Anna has little trouble climbing a tall iron fence to get into a private garden. It was established that Anna had been doing action films of late and so would likely have had physical training in preparation for those roles.
William does not have a car but Max does. William has a struggling business and needs a lodger to pay rent. Max and Bella live in a large house and she is a barrister.
After his heartbreak at The Ritz, William takes the bus rather than the Underground. There are no direct Tube lines from Green Park to Notting Hill Gate but the bus he takes actually does go direct and so would be quicker.
The friends quibble in the car about the best route from the restaurant to The Ritz. Some argue going down Bayswater, others Cromwell Road. Nobody is right - the shortest and most direct route from the corner of Golborne Road and Bevington Road is to head southeast along residential roads and drive along the south side of Hyde Park past the Royal Albert Hall. No wonder William missed Anna before her press conference.
