It may not have to be a traditional office. Sales tax law for instance considers if you have a nexus in the state as to if you need to collect and remit state sales tax.
My company has sales staff in nearly every state, yet only has real offices in one. We have to collect tax though for each individual state because that 1 employee that drives around almost every day makes us have a nexus in the state.
I'd be very surprised if IMDB would be able to get away with having only remote workers in California and not have to comply with California law.