Is rabies virus infectious outside host?
First off all we need to be 100% sure what does be infectious mean. According cambridge dictionary meaning of the word infectious is be able to past from one host organism (multicellular/cellular) from another. So this is actually biggest hole in your question.

But i think you mean something else then word infectious. In my oppinion you wanted to know if rabbies can survived outside of its host. The rabbies virus as many other viruses cannot live outside of its host. Rabbies is exists in &quot;public reservoir&quot;. This fact only confirm its variety of hosts such as bat, bears, dogs etc. (technicly all warm blood species) and its long incubation period (for example 1-3 months in humans.

According this site:

Rabies virus is transmitted through saliva and brain/nervous system tissue. Only these specific bodily excretions and tissues transmit rabies virus. If contact with either of these has occurred, the type of exposure should be evaluated to determine if postexposure prophylaxis is necessary.
Contact such as petting or handling an animal, or contact with blood, urine or feces does not constitute an exposure. No postexposure prophylaxis is needed in these situations.
Rabies virus becomes noninfectious when it dries out and when it is exposed to sunlight. Different environmental conditions affect the rate at which the virus becomes inactive, but in general, if the material containing the virus is dry, the virus can be considered noninfectious.


To sum this:
Rabbies viruses need to have contact with host, typicly by biting. It is possible to be infected by other contacts such as kissing, licking not dry saliva, but still the virus cannot live long outside of body. So long incubation and variaty of possible host (most infected is bats) makes the true killing combination.