A "Stan" eventually became internet shorthand for an obsessive fan of something or someone.
In "Stan", the titular character mentions the common Urban Legend about "In the Air Tonight" by Phil Collins, namely that it is about a situation where Collins saw a man drowning with another man deliberately choosing not to save the drowning man, and then Collins singling out the latter when playing a concert. The fact that Stan mentions this urban legend as though it were fact, despite the common knowledge that it is pure myth, rather neatly ties in with the same way that Stan perceives Eminem's Slim Shady persona to be truth ("See everything you say is real, and I respect you cos you tell it"), rather than pure fiction.
In the music video for "Cleanin' Out My Closet", Em's parents never show their faces to their camera; they always have their backs turned or have the camera too low. This could possibly mean that this is open-ended and that you can interpret anybody's faces on them.
Perhaps what Em was burying in that same video was all of the stuff he cleaned out of his closet.
In "Bad Meets Evil" from The Slim Shady LP, his song with then-friend Royce da 5'9, the end of the chorus goes "See you in Hell for the sequel." Afterwards, they had a lengthy falling out. Once their mutual friend Proof died, they patched up their issues. Cue their joint album Hell: The Sequel releasing on June 13, 2011.
Given how long it took Em and Royce to get around to making it, one can say we saw the sequel in developmenthell.
There's a realization that Eminem never cursed in "Mockingbird" because he was directly speaking to his daughters.
Until the very end where he figuratively covers the girls' ears and speaks to anyone in the audience that wants to speak ill of them...that they'll have HIM to deal with.
The last line of "Rap God" has him declaring: "Why be a king, when you can be a god." Come January 2020, he drops the song "Godzilla", which basically shattered "Rap God"'s words-per-second record. Considering that one of the Red Baron names of the namesake Kaiju is "King of the Monsters," Em basically up-ended that last line.
Stan from The Marshall Mathers LP. Not for the listener, but for the Eminem character in the song. Upon getting a letter from the eponymous Stan, Eminem writes a response back to him. Near the end (and for the character's fridge horror, keep in mind that the events of the song have already concluded while Eminem is writing the letter), Eminem writes this:
I seen this one shit on the news a couple weeks ago that made me sick Some dude was drunk and drove his car over a bridge and had his girlfriend in the trunk, and she was pregnant with his kid and in the car they found a tape, but they didn't say who it was to Come to think about, his name was... it was you Damn
And the video has, while Eminem is writing this, Stan flash in the windows of the train, watching him....
One line that Stan says, saying "He (Stan's brother) likes you more than I do". Now, having seen how bad Stan's obsession with Eminem was, imagine how bad Matthew's could be....
What exactly was Eminem burying in the "Cleanin' Out My Closet" video?
A body, from what's implied, albeit what could be presumed metaphorically
Imagine what was going through Kim's head when she heard "Kim".
You don't have to. She flat out admitted in an interview in 2007 that she heard the crowd at a live show shouting "Bleed bitch, bleed!" and immediately went home and tried to kill herself.
In "Cold Wind Blows" from Recovery, which was released a year before Hell: The Sequel, there's a few lines where God tells Slim Shady that He will send him to Hell if he does not change his ways. Apparently, he didn't.