If there is no laugh track then why do some of the outtakes have no... laugh track? Also, you can clearly hear studio audience laughing on some of the outdoor scenes. Did they get the audience to accompany them outside - "come on people - get your coats, we need you outside for the next 5 or 6 hours whilst we do take after take after take of the same scene".
Why, hey? Why?
The outside shots are recorded without an audience but shown to the 'live' audience for their reaction before they film the interior shots. In that sense it is a laughter track, but not 'canned' laughter (in other words the laughter is generated by the scenes being shown, not just by pressing a button on a console.)
The full set up of the audience and 4-wall set design is explained on the DVD release, during the writer's commentary.