Are there any diseases that appear to be kawasaki disease but are actually something else?

Many. Diseases with features that are similar to kawasaki disease include: viral infections such as rubeola, roseola, rubella, adenovirus, bacterial infections such as streptococcal scarlet fever, staphylococcal scalded skin syndrome, toxic shock syndrome, lyme disease toxoplasmosis rocky mountain spotted fever typhus juvenile rheumatoid arthritis drug reaction.