 The episode was shot in Vancouver during the summer , where temperatures were over 100 degrees Fahrenheit . Executive producer Jeff Pinkner commented that despite the heat , guest actor Leonard Nimoy " was doing pages and pages of dialogue , and he handled it like a pro , " while co @-@ star Joshua Jackson joked that " [ Nimoy 's ] wife said he practices biofeedback , so he knows how to control his body temperature " . Chappelle called the episode " intriguing because it 's a summation of everything that came before it , so we 're resolving a lot of issues and a lot of questions . But it 's also a springboard into the rest of the season " . Actor John Noble , who played Walter Bishop , called it " probably one of our strongest and densest episodes " because it " changes the whole direction of the show " . 
