When Farnum sees the gold coins ("squandros") pouring from the mouth of the animal head on the wall, he and Will see a second animal head further to the right begin to spew coins. When they immediately walk over to the second animal head, the container is nearly full despite the coins just having started to fall.
After Major West tells Dr Smith to read the fine print in Judy's beauty pageant contract, Major West runs outside to check on the starship that just landed. As he runs away from the Jupiter 2, his shadow can be seen crossing the fake background scenery.
Farnum calls Will "Billy" by accident.