1) First crossover
The episode starts in London, in the midst of the clean-up following Thor: The Dark World. Those dark elves made quite a mess of Greenwich, very cool to see a follow-up to events in Thor.
2) Skye and May both like the look of foxy Thor
Well, he is a bit of a babe.
3) Ward finds a bit of Malekith's ship
He stores it in a box for safekeeping, like intergalactic tupperware.
4) The park sign
In a super-awesome little in-universe reference, the motif on the public park sign is an altered logo from Lady Sif's red outfit from the comics.
5) The Asgardian Staff
Prof. Randolph explains that the team have found a piece of Beserker Staff (and he should know!) Who would win in a fight between Marvel Beserkers and Lord of the Rings beserkers? Discuss.
6) Dollhouse reference
Seriously underrated Whedon show Dollhouse is one of my fave less-watched TV shows, so it was very cool to get this nice little tribute to the show with the interchange 'Did I fall asleep?' / 'For a little while.'
7) The Chitauri
Only a brief mention is dropped in Agents of S.H.I.E.L.D., but I'm sure we'd all like to see more of Loki's army! Also available as toy figures...
Probably the randomest occurence in this Agents of S.H.I.E.L.D. episode, Hindu God Vishnu is mentioned in passing by Skye. Vishnu is a character in the Marvel Comics, featured in Thor #300, but you knew that.
Another quick mention, but the Marvel Universe supermetal, most associated with Captain America and Black Panther was a titillating name drop.
Kudos to Comicbook.com for teasing out the many Thor and Marvel references.
Share if you are a mega-Marvel fan who totally spotted all this stuff.