Ronald D. Moore's original idea was for Jeremy Aster to recreate his mother on the Holodeck. However, Gene Roddenberry nixed the idea, believing in the 24th century children would have a greater acceptance of death.
Star Trek debut of writer Ronald D. Moore, who later rose to stardom as creator of the acclaimed, re-imagined Battlestar Galactica (2004).
This episode contains similar themes to Stanislaw Lem's 1961 novel "Solaris".
When they're scanning the planet, you see Valles Marineris on Mars.
Patches is a calico (tri-color) cat. Jeremy refers to the cats as "he". Most calico cats are female. This is because coat color is partly determined by a gene on the X chromosome. Male calicos may have Klinefleter's syndrome (two X and one Y chromosome, in some or all of their cells, instead of XY). Some male calicos have no chromosome abnormalities. Of course, being the future, it could also be genetic engineering.