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.


 * 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.
 * 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.