Duchovny started shooting the movie's action sequences two weeks before Anderson arrived on set. "We were running around doing crazy stuff and it didn't really feel like The X-Files to me so much, but then when I started to work with Gillian it sunk in," he says.
Anderson says: "We'd seen each other in between and we did a week of rehearsals in LA before David started, so we got an opportunity to gauge where we were at. Fortunately, that dynamic was still alive, so that when we started shooting again, it showed up when we showed up."
Duchovny laughs and says: "We couldn't keep our hands off each other."
source article contains mild spoilers!