In season Four episode "Playmates" - a non-Darrin episode. It appears that Samantha's reactions to Tabitha's spells were filmed separately than Tabitha's reactions. The same wagon and large duck toy can be seen in both shots.

https://i.postimg.cc/BQ2wK8Gy/sam.jpg

The kids were probably filmed separately and quickly since there was limited time they could work. Which is why you see Liz talking to Tabitha from across the yard set - then a cut to Tabitha. Or the set decorator bought two of some things...

Ahhh...another blooper we discovered. I guess there are more of these than we thought!

In season Four episode "Playmates" - a non-Darrin episode. It appears that Samantha's reactions to Tabitha's spells were filmed separately than Tabitha's reactions. The same wagon and large duck toy can be seen in both shots.

The kids were probably filmed separately and quickly since there was limited time they could work. Which is why you see Liz talking to Tabitha from across the yard set - then a cut to Tabitha. Or the set decorator bought two of some things...

Look closely at the wagons. Different wheels.

Look closely at the wagons. Different wheels.

I believe that is the studio lights hitting the white wheels differently. As the wagon moves around they change reflection.

https://i.postimg.cc/PJgdt090/ww.jpg