First, keep an eye on the top right hand corner of the screen in this shot and you’ll spot the boom mic shadow…
Next, it looks like this particular Sensorite could do with some more hair to help hide the fact that he’s really a human in a mask!
Now here’s a cracker – when the Sensorites are pursuing Ian and Barbara, they don’t need to bother going through the doors , they can just swing open that loose panel in the wall…!
Here’s boom mic shadow #2…
That shadow you can see on the floor is the camera getting a bit to close to Ian as it moves in for the close up…
And to finish off, here are another couple of boom mic shadows from part four…
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You are also forgetting the first shot of a sensorite, the space background can clearly be seen to be stretched canvas and also the photosensor on the wall was clearly about a foot to the right originally
the marks from the drill were also in the bulkhead door from the word go