Despite Ein's enhanced intelligence, he remains incapable of speaking (other than barking). Because of this, his intelligence largely goes unnoticed. It does seem that Ed understands Ein through his body language and barking, however this is never made explicit. Ein also barks once for yes and twice for no.
- All of Ein's vocalizations were done by a Cardigan Welsh Corgi named Jack, owned by the show's producer Kazuhiko Ikeguchi.
- Given the dog's highly intelligent nature, the name "Ein" is likely short for "Einstein".
- Ein's popularity on the show has resulted in an upsurge of Welsh Corgi's named "Ein."
- Another possibility is that the name is the German translation of "one", in the meaning of him being considered a he or an it. It can also be interpreted that, in Japanese, the way dogs bark is "wan" (ワン, pronounced the same as "one"), hence the name "Ein".
- An allusion to Ein appears in the Rooster Teeth series RWBY through the character of Zwei (a dog of similar breed and intelligence). Eins is the German word for "one" while Zwei is German for "two".