You can apply for a Vietnam e-Visa online and collect the physical visa on arrival in Vietnam itself. Specifically for Mumbai, you can actually visit the Consulate of Vietnam and apply for a physical Visa there. Its address is Wajeda House, Gulmohat Cross Rd. No.7, Juhu Scheme, Mumbai - 400 049, Bombay, INDIA.
Check this link for more: https://www.tripoto.com/trip/two-weeks-in-vietnam-and-cambodia-565f5f8459bae
You can apply for a Vietnam e-Visa online and collect the physical visa on arrival in Vietnam itself. Specifically for Mumbai, you can actually visit the Consulate of Vietnam and apply for a physical Visa there.
Hope you had a great journey, please do share your experience with us, so that we can know better about places, and plan accordingly while we travel next to that city.....keep exploring