The memory recall interface in the Arkangel program when Marie is reviewing Sara's memories is similar to the Grain memory interface in The Entire History of You (2011).
A stuffed "Waldo," the character from The Waldo Moment (2013), can be seen in Sara (Brenna Harding)'s stroller when the two enter the park.
The director, Jodie Foster , became a child actor at age 3 and so (like Sara) was observed, monitored, and recorded by cameras throughout her entire childhood and adolescence. Also like Sara, Foster was subject to the obsessive attentions of at least one stalker (although in Foster's case, the stalker was a stranger, not her mother--a mentally ill fan who tried to assassinate President Ronald Reagan to impress her).
In episode 4.6, Black Museum (2017), one of the museum exhibits is the smashed Arkangel tablet Marie (Rosemarie DeWitt) owned.
A lunchbox displaying Waldo can be seen when Marie Rosemarie DeWitt takes Sara Brenna Harding to the playground in her buggy.