During the marina flashback, Sayid says only to Ben, "If I see you again, it will be extremely unpleasant for us both, while in This Place Is Death (2009) Sayid addressed both Jack and Ben by saying, "If I see you, or him again, it will be extremely unpleasant for all of us."
In the scene where Sayid kills a Russian guy, the latter is seen entering the house with a paper groceries bag. Russian stores and supermarkets ONLY use plastic bags, usually with the store/market logo on it. Paper bags have never been used in Russia/USSR.
In the scene where Sayid kills a Russian guy, the whole apartment is not Russian. Furniture, apartment layout, doors, door chains - everything is "what Americans thinks Russia looks like". It couldn't be further from reality.
When Sayid meets Ben in Moscow, the number plate on a car seen behind Ben is wrong. The region code for Moscow should read 77, 99, 177, 197 or 199. Code 156 hasn't been assigned to a region yet. Also a Russian tricolor flag right above the region code is missing.
Ben brings Sayid a sandwich. As Ben hands the plate through the bars, the plate makes the sound of a china plate being scraped. However, it's obviously a paper plate. In a later scene, the same type of paper plate is heard shattering against a wall.
The computer seen in the background of the Dharma security room is an Apple Lisa II/Macintosh XL which wasn't produced until 1985, about eight years from the time the action in this episode takes place.
The CCTV camera outside Sayid's holding cell is a quite modern design that's only possible with small CCD sensors, that weren't commercially available before 1980. Such cameras were much bigger in 1977.
When Ben and Sayid talk in Moscow, St. Basil Cathedral and one of the Kremlin towers can be seen in the background. The place where they would be talking in real life is one of the most famous (and busiest) places in the world, Red Square, not the ghetto-block that is shown.