I believe this episode could be successfully summarised in but one word: confusion. Normally points of particular interest and "easter eggs" can be picked out, but with this one it seemed like the whole thing was mystery. Was it a flashback? Was it deja vu? Did Desmond go back in time? Who the heck was that woman? Who the hell wears a business suit with bright red converse?
As a Brit, I felt this episode of course leant to my usual moan of "god Americans think THAT is London". Apologies for popping the view, but I haven't seen a roast chestnut stand... well... ever, and must admit, can't say I've ever tried it (I'm sure I must be living a sheltered life though...). Equally, its much more likely that a thug in a hooded jumper would have stolen the money from Charlie's guitar case, etc etc. In fact probably one of the few representations I believed was the man with the baseball bat lol! Its good when you take pride in your own nation, isn't it?
So anyway, let's try to pin down some of the things in Desmond's dream/flashback/journey to the past/concusssion/who knows. I'm going to try and note Lost-shoutouts (if you get me) and other continuity issues. These are just the ones I noticed, so there's probably plenty more other Lostpedians found:
* The clock says 1:08 in Penny's flat.
* Penny says "the end of the world".
* The microwave in the flat makes the same sound as the Swan alarm.
* A parcel is delivered for 815.
* The artwork in Widmore's office shows a polar bear, mountains, a Buddha, and the word NAMASTE.
* Desmond begins to say that he couldn't go to University after his father... (died? became ill?)
* Desmond seems to lie about having military experience (or possibly didn't join up until after the events? A bit unclear...)
* Widmore mentions the race around the world. He also refers to the Widmore company as "his foundation", which would make it the Widmore Foundation.
* Widmore discusses his drink - a possible connection to Arthur Widmore in the Bad Twin novel, who seemed to be a connoisseur of good whiskey.
* The song "Make Your Own Kind of Music" plays in the pub.
* In the ring shop, a faint ticking can be heard, probably from one of the clocks. The sound is identical to a ticking sound that could sometimes be heard in the Swan computer room.
* The woman says pushing the button was the only truly great thing Desmond will ever do.
* The photo stand has a "15" on the top side of it.
* The photo previously seen in other episodes is taken at the photo stand.
And that was it. Gotta say it was nice to learn a little more about the Widmore Corporation. I was hoping to see Rachel Blake in the background, on exchange to the UK branch - but hey can't have it all. But of course the biggest "huh" in this episode was reserved for the woman. Was she a Doctor Who time traveller? Or maybe, as one theory I liked states, she was involved in the incident and got shot back in time like Desmond (bit of a stretch, but I don't see any more logical explanations!).
Lastly, to the final scene. So after Desmond returned he continued to have odd flashes - only this time of the future, I assume? Like the woman said about fate, Charlie is destined to die like the red Converse man. Can Desmond change the future? He saved the man from getting hit by the baseball bat, but that sent him back to the Island?!
Basically, this episode just confused more than anything, and we still don't know what happened to the Swan, why Desmond woke up nude, and why he can see "flashes". Gotta say I'm the man of science, and so would like to see more of the mundane Hydra Island high-tempo action with Jack and co. than the tame vision approach of Desmond and Locke. I thought they would be going to the Flame station as well, as John said in "I Do" he wanted to make a stop on the way back. I guess maybe that's a flash for a future ep...