When Gray flies off on her mission, she boards a Douglas DC-3 Dakota - but the next in-flight shot is of a Vickers Varsity.
When Lockwood and Clark go through a check point their passports and car are checked and the guard phones the next check point before allowing them to proceed but when they later repeat their journey the guard doesn't phone through.
All the guards - road and laboratory - are carrying machine-pistols, but the soldiers who find the car are armed with rifle with fixed bayonets.
When Casey and Conway take the soldiers to fight the fire, the soldiers are only carrying their weapons. But when the soldiers arrive at the fire, they are all carrying brooms to extinguish it.
At about 1:16, as Clark/Lockwood are about to emerge from the woods, they have a short dialogue re the insects and why/how/etc. Immediately after Clark says,"They're just insects," he rises from a squatting position and what sounds like a mellifluous bit of flatulence can be noted.
In the research station, when Casey interrupts a game of chess, the chess board is the wrong way round.