I'm so sorry to hear about your furbaby! I don't know offhand if he's sick but I googled canine rabies vaccination side effects...
(from
http://www.knoxvet.com/FAQ.html#VaccSideFX)
"Most modern vaccines have minimal side effects, although some individuals will react more strongly to a vaccination than others. The most common reaction seen among those pets who have a reaction is a short period of lethargy (increased sleeping and inactivity) or mild fever. If such a reaction occurs, a wait-and-watch attitude is usually the best way to respond - they will feel better in a day or so.
Some might develop a local reaction in the skin, which is usually a pea to marble-sized firm lump under the skin. These reactions can show up anywhere from a few days to a couple of weeks after the vaccine is given, and although usually nothing to be overly concerned about, they should be brought to the attention of your veterinarian.
The most serious short term problem which could happen is a strong allergic (anaphylactic) reaction. These reactions typically occur anywhere from 5 minutes to several hours after the vaccination is given. In dogs, this generally has one or more of the following symptoms: hives, extreme itchiness of the face and skin, red splotches on the skin, pale tongue and gums, difficulty breathing, and sudden weakness. Although an antihistamine may help slow down the reaction, if your dog has any of these signs it is very important to have him or her checked out as soon as possible. Cats rarely have this type of reaction, but it is possible and should be examined if noticed.
Overall, these reactions occur very infrequently. The diseases the vaccines help prevent are a much more serious threat to your pets' health than the potential vaccine reaction. If you have any concerns or if your pet has a 'family' history of vaccine reactions, please discuss the issues with your veterinarian."
The only thing I would say is if your vet accidentally administered another vaccine, maybe you should look into another vet.