Stephen Root and Romy Rosemont, who play husband and wife Raymond and Kate in this episode, are also married in their off-screen lives.
The glyphs for this episode spell out: LIVING
Raymond has 47 minutes at a time with his wife. The number recurs many times during the series and was also a key number throughout the run of J.J. Abrams' Alias (2001), though the motif originated in Star Trek: The Next Generation (1987), with multiple references.
In the lab, Water comes out to make a baloney sandwich. As he heads back, he takes "Carroll's Cosmology" from Peter. This is an actual book by Sean Caroll, a renowned cosmologist.
The Observer can be seen walking on the sidewalk in front of the apartment building in the opening scene of the first time incident with the mother and daughter.