It is not irrelevant that the characters are rabbits.
You would simply state that clearly.
Think about a movie featuring a female lead. It is usually not said in the movie what gender that person has, because (in most cases) this is apparent, yet in a novel you would certainly not hesitate to clearly indicate that the protagonist is female, either by name (if that name is gender specific) or pronouns or, if necessary, by stating the fact. Age and gender of a character are of prime importance to the readers, and keeping them ambiguous is always done intentionally and to a purpose.
David Lynch does not leave any doubt about wether or not his characters are rabbits, and so you shouldn't either. Since we have no pronouns or names that indicate rabbitness, you must, in my opinion, use the word "rabbit".
Hildred's example may work, because the sheer quantitiy of hints (bunny, ears, paws, hind foot) points in the right direction, but since "bunny" is not exclusively used to allude to rabbits, nor are rabbits the only animals with ears, paws and hind feet, I'm not sure if I wouldn't rather have thought of another animal (or thought this strangly bad writing) a long way into the novel, before the true nature of the characters would finally have dawned on me.
But, as hildred also noted, the clear indication need not be in text. It could be in the cover illustration, the blurb ("A tale of two rabbits ...") or the title ("The Maltese Rabbit").
You must not confuse showing things to the viewer in a movie with "showing (not telling)" in written fiction. If something is clearly seen on a movie screen, that corresponds to "telling" in fiction: the movie shows a car parked in front of a house; the novel "tells" us that a car is parked in front of a house.
"Showing" in a novel is done in the same way as in a movie: by implying facts through the actions of the characters. You "show" that a person is in love by letting them blush when they encounter their crush, both in a novel and in a movie.
In fact, movies cannot easily "tell" us certain things. You would need a voice over narration to tell us that a character is in love. Since voice over narration is unpopular in certain movie genres, "showing" is necessary in those movies.
This technique has invaded certain genres of fiction writing with the use of other cinematic techniques.