First time going out solo with baby - advice needed

My son is 2.5 months and my wife is going to her work thing next Saturday for 4 hours. This will be the first time I'm alone with him for a substantial period. What am I missing? I've obviously got diapers, wipes, formula, but should I bring extra clothes? A change mat for the car? I'm probably overthinking this but ngl I'm a bit nervous lol