The actors play boozy married couple Kate and Charlie Hannah in James Ponsoldt's new drama and they hired the director as their designated driver as they planned a bender in a bid to get to know each other better before filming began.
The Breaking Bad star organised the night out with Winstead and asked Ponsoldt to document their evening for research - and make sure both got home safely.
Paul admits reviewing the footage the next day was sobering.
He tells Reuters, "It's incredible what alcohol does to you; after each drink, you truly change quite a lot. I'm definitely a happy drunk. I'm very loud. But it was somewhat painful the following day."