In Beaver and Ivanhoe Beaver is walking down the street and there is no sign on the sidewalk when Beaver sees the dog and the girl getting pushed down. Then a second later when Mr. Crawford jumps off the bus there’s the sign.

I remember the scene but I didn't notice that.

And you're right Penny is unnamed in the script. June said they were a new family. The boy is in the fifth grade, but there is no sign of unnamed Penny in Beaver's class.

Right Penny was Beaver’s age. Later in Beaver’s Team they have another kid play her brother. I like how there’s a new kid in town and we never see them again.

Like Kenneth Purcell, Dudley MacMillan, Ginny Townsend, Mary Tyler, etc.?

You would think Dudley would have really been around Mayfield being a dreamy piano player. I can see Dudley as a Crusader and playing piano at Hank’s.