Strange Days takes place in the same universe as AvatarThe SQUID was developed by the government for covert surveillance and military/police training purposes according to the film. Somewhere along the line, they adapted the technology, allowing users to control actual living (albeit empty) entities for alien colonization.
Strange Days takes place in the same universe as Dark AngelThe presence of SQUID technology in the late 1990s makes all the advanced technology in Dark Angel (such as Manticore's genetic engineering tech) seem more plausible for the early 2020s. The societal conditions in Dark Angel could also easily be seen as the logical extension of those in Strange Days; it's not hard to imagine America limping along as it was in the film for another ten years before the Pulse finally pushed it over the edge.
Strange Days is a continuation of the world of the 1983 film BrainstormBrainstorm shows the initial development of the SQUID sensorium-recording technology as well as the government's interest in it. Early in Strange Days, it is mentioned that the technology first appeared as a replacement for the standard concealed recorders used by police.
The novel Damage Time by Colin Harvey is set 50 years into the future of Strange DaysBoth novels feature readily available memory recording, which by the era of Damage Time has developed further into full on memory-ripping (i.e. recording and erasure of memories). Both featuring a decaying USA, although Damage Time is more decayed, as it is set after the oil has not quite, but almost, entirely run out, and California has seceded from the union.
The three women beating up a dude in a Santa costume near the start of the filmIt may actually just be the mugging it appears to be... ...or maybe Santa just said "Ho, ho, ho," at exactly the wrong time.