Duck_of_Death needs to watch this film again, as his major criticism is completely baseless. The film never once forgot about the time delay, and it was mentioned explicitly in a couple of places. The crew were never shown having conversations with mission control that didn't obey the time delay rules.
One thing I did think was a bit far-fetched was the amount of risk involved - would a crew land on a planet on which pressure suits would only last two hours? I doubt it. Would a manned space ship go into a star's corona? I doubt it. Would humans land on a moon that was being bombarded with huge amounts of radiation? I doubt it. Also, the ship seemed overly sturdy. Would a ship designed like that risk atmospheric flight to slow it down? I doubt it. Would it survive being hit by comet debris? I doubt it. I think in both cases the stresses on the structure would be too much. But all-in-all, the unlikely scenarios were compensated by some nicely done special effects, good editing and production, and some good acting, especially by the actors portraying the ship's commander and the Russian cosmonaut.