Whichever character is NOT leaving will find out that the other is and will be required to make an obligatory mad dash to whatever location they are leaving from, in order to stop them. The zanier the mode of transport they can acquire to do this, the "better" the moviemakers feel their romantic comedy will be. Why simply drive to your required location when you can be taken there by a stereotypical ethnic minority in a taxi? Why take a train when you can comically hang off the back of a horse or motorbike being driven crazily by a minor character from the first two acts who's popped back to 'save the day'? Why walk with a sense of purpose when you can run and fall over fellow pedestrians or humorously ill-placed everyday objects?