When the Doctor first arrives in the bunker, he's wearing a long brown overcoat over a shorter red jacket. We never see him remove the overcoat. But a moment later in the same scene the overcoat is gone and he's seen only in the red jacket to the end of the program.
The big rocky wall visibly shifts when Sarah leans against it at the end.
Why do the Thal soldiers wear camouflage gear, yet paint their gas masks a garish red and yellow?
When Davros is showing the Dalek under voice control for the first time, his lips don't move after giving the directional controls to the Dalek.