There's nothing quite like being timeless. It's the highest compliment one can bestow upon a work of art. Nothing destroys timelessness more than pop culture references because you're essentially dating your art with the current event. If I mention Paris Hilton, you can tell my piece is from the early 21st century. Every now and then, someone can date their art so well, that the fact that it's sooooooo dated, almost makes it timeless. A good example of this is Weird Al Yankovic. If you listen to any of Weird Al's spoofs, the song is filled with other references to that year, i.e., that "Lump" song which he remade as "Gump" and is the perfect relic of the mid 1990s. The datedness is pure genius.
Tarantino is a different cat though, and even though he's already made some timeless movies, he intentionally undates (not a word) them. In Pulp Fiction they go to a 50s restaurant even though with large early 90s cell phones also appearing in the movie, you know it's a throwback restaurant, but at the same time, this movie doesn't necessarily have to take place in the 90s either. Kill Bill Vol. 2 has Darryl Hannah driving a 1980s Transam complete with golden eagle on the hood, but again, also has cell phones. It's almost as if Tarantino makes his movies as taking place some time between the 50s and 1990s and WANTS to make the viewer unsure.
The best example is Jackie Brown, which though it's quite clear it takes place in the 1990s, it does some pretty strange things. For instance, Max is still buying cassettes in the mid 1990s, which is significant because cassette sales plummeted in the early 90s. Tarantino does this to show how "old school" Max is, but he also inadvertently dates his pieces to an era in which cassettes can be purchases at chain music stores in malls (also on the decline), which is an era from the 1980s, to the late 1990s. I'm not sure if you can go into a music store in a mall anymore and buyer a cassette. If you can, I'm sure that section is tiny. Cassingles however, are more popular than ever … okay, maybe not. I may have owned a cassingle or two, maybe Bell Biv Devoe's "Poison" which was purchased accidentally because I mistook it for a new song by the band Poison titled "Bell Biv Devoe." Hell, it was around the same time they released a song called "Unskinny Bop" so anything was possible.
Something else that strikes me as an inadvertent film dating, is Jackie is smoking in the mall.