Theory:Doctor Who television discontinuity and plot holes/The Seeds of Doom


 * The TARDIS returns to Antarctica at the end of the story, the Doctor having not re-set the coordinates - but the TARDIS never went there in the first place (he and Sarah traveled by helicopter).
 * He had originally planned to travel there using the TARDIS and set the controls accordingly, but Sarah Jane talked him out of it, considering the urgency of the situation and that the TARDIS often misses its intended destination.
 * Or alternatively, the Doctor did indeed use the TARDIS to get to a central base in Antarctica, after which a helicopter took him and Sarah the short remaining distance to the camp - this seems to make sense because the Doctor would definitely know the location of Antarctica, but not necessarily the location of the camp. There's no way they could travel the entire distance from Britain to Antarctica by helicopter, so presumably they travelled at least part of the way with another mode of transport -- why not the TARDIS?


 * After the composting machine processed a human, the machine was still clean of blood or gore entirely. No splattering either while it was in operation.
 * Perhaps a self-cleaning machine?


 * Given Chase's views about plant welfare, it's unlikely he would have topiary in the grounds of his house.
 * People are often hypocrytical in various regards.


 * A rather convenient selection of plant come to life. UNIT escape beyond one set of plants - yet more can clearly be seen behind them. Similarly when the Doctor and Sarah Jane run from one set of live plants, the escape from them - only to have another set of not-live ones clearly visable behind them.
 * The Krynoid is only one being, and he is directly controlling these plants, just because he's the size of godzilla, doesn't make this task any easier, I mean considering all the plants there are, think how much of a mental strain it must be to control there movements to coinside with each other. After all when the doctor said all the plants out there are against us, he didn't mean all of them were, just any of them could be.


 * Chase talks about how great the world will be, after being possessed, about the krynoid and its offspring, whipe out all the animals, and return the world to a land of plants, it never seems to occur to him, without animals to provide the plants with carbon dioxide, that all the plants will die within a few centuries, less time considering how much ones the size of the krynoid would take in.
 * Not really. Animals need plants, but plans don't necessarily need animals to get their Carbon Dioxide - assuming the Krynoid, an alien plant which could survive being buried in ice for hundreds of years, even works the same way as Earth plants.
 * Also the Krynoid isn't interested in creating a plant paradise on Earth. From what the Doctor said, it consumes all animal life and moves on, most likely through germinating spores into space.  Chase is either mad or is being manipulated by the Krynoid to believe it is there to create a paradise for plant life.
 * I mean, the operative words here are after being possessed. The man is being literally mind-controlled and driven mad by a genocidal sentient vegetable with a vested interest in wiping out literally all animal life, if we're demanding that he suddenly start questioning the logical foundations of the plans of the alien lifeform basically using him as a puppet we're asking too much of him frankly. He's literally not in control of his own thoughts and actions, of course he's not going to be approaching them rationality in terms of scientific plausibility.


 * After being in the snow overnight, I understand that the Doctor would survive, being a Time Lord but Sarah Jane should have frozen to death/died of hypothermia yet it seems that she is fine.
 * It looks like daybreak by the time the Doctor and Sarah were out in the snow. And as the rescuers mention hearing the explosion, it is likely they were nearby at the time and came quickly.


 * Brandy is not recommended treatment for hypothermia, and one would assume late 20th-century Antarctica-based scientists would be better-versed in such situations than working-class junior lighthouse keepers from c.1902 (cf. "The Horror of Fang Rock"). Apparently not, though...
 * Where is it said that anyone's suffering from hypothermia? Brandy is often served warm, and everyone we see who gets a stiff toddy is otherwise healthy and in the process of being warmed up in other ways. They're basically just giving their guests a quick warm drink in order to be hospitable.