The matchbox and seed packet are, relatively speaking, much further apart when shown in normal size than they are for the miniaturised Ian and Susan.
There is a visible gap in the backdrops of the TARDIS control room set.
Vertical joins can be seen in the rock face scenery.
When the Doctor is looking over the paving stone, wrinkles can be seen in the painted backcloth.
When Ian walks past Farrow's head, Ian's head becomes transparent when he passes Farrow's nose and upper lip, revealing the effect to be a multiple exposure.