The over-riding problem with this film is that it can't possibly use Bill Murray to the best of his abilities, simply because of the co-star.
If this was a road movie with another comedic actor, it might work. Even if they were both trying to get the elephant across the country, it would at least allow for them to share some amusing dialogue. As it stands, Murray is left talking to an elephant who cannot answer back with witty banter. Essentially, it means that Murray is talking to himself, and this makes the film more boring than it could have been had he had another character to bounce off.
Kids would enjoy this movie,simply because of the elephant, but anyone wanting to watch Bill Murray's biting delivery and enjoy an excellent script needs to look somewhere else.