From the DVD commentary, episode 1:
Douglas: Those [bottles] really are filling up, that's not CGI, those really are bottles of wine filling up from the bottom - our wonderful effects company, SFX actually put pipes to the bottom of the bottles of wine.
Neil: They did. People keep asking me, if they do it like that, are they allowed to re-drink the wine, once they've...
Douglas: You wouldn't want to, would you?
Neil: Ahh, once you magicked it out of your system...








