Here is all the detail I managed to find on the Somewhere in time cover:
* "This is a very boring painting" - backwards message just behind Eddie's right leg
* Ruskin Arms reference (old pub they started playing at)
* Clock says 23:58 (2 Minutes To Midnight)
* West Ham 7 Arsenal 3 - soccer score, showing their favorite team West Ham
well in the lead. Incidentally, West Ham are THE IRONS - see section 24
* Aces High bar, complete with a spitfire flying above.
* The Rainbow bar (another old club they frequented in the early days)
* Live After Death, Blade Runner on the movie theater
* The movie theater is the Philip K. Dick cinema, who is the author of "Do Androids Dream of Electric Sheep?", on which the movie Blade Runner is based.
* Marquee Club (another old club they frequented in the old days)
* Phantom Opera House
* "Bollocks again and again" under "Phantom Opera House". This might be a reference to the hidden "Bollocks" message on the Powerslave cover.
* Ancient Mariner Seafood Restaurant
* Herbert Ails on the overpass (probably a reference to Frank Herbert, author of DUNE, who wouldn't allow Maiden to use it as a song title).
* "Tonight GYPSY'S KISS", under the 23:58 sign (hard to see) - reference to Steve Harris' very first band
* Hammerjacks - a reference to one of the band's favorite bars in the US, Hammerjacks Night Club in Baltimore, MD. The Night Club closed on Jan 1 94. The concert hall is still open, however.
* Long Beach Arena
* Nicko is dressed in old-time flight goggles (reference to him being a pilot).
* Nicko is also wearing a shirt saying: "Iron What?"
* On the back cover there is Icarus falling from the Sun with burning wings in the top right corner, in front of the Bradbury Hotel. This of course refers to "The Flight Of Icarus."
* The "Bradbury Hotels International" sign - is this possibly a reference to the popular futuristic author Ray Bradbury (author of such classics as "The Martian Chronicles", "Ice Nine", etc.)?
* If you look closely, you can see the shadow of the reaper on the back cover in front of the pyramids.
* The pyramids refer to the sleeve of "Powerslave".
* All the Japanese around the covers could be connected to "Maiden Japan" and IRON MAIDEN's other performances there.
* "Maggies revenge" on the back cover refers to Margaret Thatcher. She and the British government had a dispute with IRON MAIDEN back in 1980/1981 with the "Sanctuary" and "Women In Uniform" singles, depicting her as dead
on the ground (killed by Eddie, of course) and hiding behind a wall observing Eddie picking up chicks, respectively.
* The street Eddie is standing on is Acacia Avenue, a reference of course to "Charlotte the Harlot" and "22 Acacia Avenue", the Charlotte series. (You can see this above the IRON MAIDEN poster on the extreme right side).
* In one of the windows on Acacia Avenue, you can see a girl (supposedly Charlotte the Harlot herself) sitting in a chair.
* Bruce Dickinson is holding a brain, ala PIECE OF MIND.
* Tehe's bar is where they got the guys to sing backup vocals in the sing- along part in "Heaven Can Wait."
* Batman standing under Tehe's bar sign
* Tardis from Dr. Who is above the Rainbow Club sign
* Asimov Foundation Building in background
* Tyrell Corp. right above the causeway (replicant manufacturer in Blade Runner)
* Cat with halo, which seems to pop up all over the place
* Eye of Horus above Webster sign to left of Eddie's gun
* One of Eddie's eyes is actually a 'laser'. This probably comes from the "2 Minutes To Midnight single"... Just remember the picture from this single:
Eddie has a "pirate's eye", probably because of the nuclear holocaust (the nuclear mushroom-cloud in the background).
* There is a litter box right under Eddie's left leg attached to the
lamppost. This is exactly the same as the litter box attached to the light post on the IRON MAIDEN debut album, to the left of Eddie next to the wall. Pretty obscure!
* Also, there is a metal plate that connects Eddie's nose to the top of his head. If you look at the wall to the right of sign that has the football (excuse me, 'soccer' for y'all in the US!) score on it, you will see that little metal plate with two screws that Eddie always has on his head (since the PIECE OF MIND era at least, when he was lobotimized. The screw is there now to keep his head all together in one piece!).
* There are also these neon signs, one of which says something in Hebrew, the other one in Russian. The Hebrew bit probably means "God" (?), the Russian bit is pronounced KEPHIR and means "yoghurt". This is (or rather was) a rather common sign on the buildings indicating a milk-store in Russia.
If you find any more just post it in.