The Sleestak feet are much larger and longer in this, their first appearance, than they are in later editions of the series.
Just before Rick and Cha-Ka enter the net room, the flame of the torch is nearly burnt out. When they enter the room it is glowing brightly again.
It is a longstanding fact in the series that the Sleestak are terrified of light and are, thus, unable to leave their caves during the daytime, yet three Sleestak capture Will and Holly in broad daylight.
After Chaka leaves Will and Holly because he is afraid of the sleestak, you can see him peek around the left side of the rock when he is supposed to be out of view (apparently Philip Paley thought he was).
When Rick and Cha-Ka are searching for Will and Holly in the Sleestak caves, a Sleestak is able to sneak up on Rick without Rick hearing it; the Sleestak is silent until Rick sees it. This should be impossible, as the Sleestaks' raspy breathing is very loud.
Although all the Sleestak carry crossbows and quivers full of bolts, none of them ever attempts or even threatens to use its crossbow on any of the Marshalls, even when Rick is unarmed because Cha-Ka is using Rick's torch to fend off another Sleestak.