To offset the cost of the lavish jungle sets in this story, the Morestran interiors were made on a shoestring budget, and, unfortunately, it shows. However, the production team does its best by at least putting the sets on different levels.
The exterior of the ship requires the climbing of two ladders to reach the hatchway, there's a staircase outside of Professor Sorenson's room which offers the antimatter-infected Sorenson to stagger up and down for dramatic effect, and the command deck of the ship is also a multi-layer affair. This offers director David Maloney the ability to shoot scenes in a variety of different ways that draw attention away from the fact that most of the Morestran corridors and walls are made of cheap, grey flats. In a programme with a small budget like Doctor Who, such directorial ingenuity is essential.
Tom Baker and Prentis Hancock perform a brief fight scene scene towards the end of this episode that still impresses me to this day. It happens right outside the TARDIS, when Salamar is distracted momentarily by the distant screams of Sarah Jane, and so The Doctor seizes his moment and clocks the Morestran commander. It's expertly shot on camera to conceal the fact that Baker never hits Hancock, but the punch is so well timed that I'm never entirely sure that Baker didn't actually hit his fellow actor. There's even a sound of...something at the moment of impact that could be the sound of Baker's fist hitting Hancock's jaw, as overdubs of sound effects for studio recordings were still an extreme rarity when Planet of Evil was made.
While I'm sure that Baker most likely did not hit Hancock, the fact that I even need to question it makes the scene a very effective one indeed.