Several packets of Panadol. Had a 3 week toothache on Cape York once.
Supa glue for closing wounds.
Extra of any medication this old fella might be on at the time.
If doing a lot of driving in hot weather, a laxative can come in handy. Oh
and something to effect the reverse action :)
Something for the tummy, I'm a lousy cook and local food is often only fit
for the locals.
If in hot , dry , sandy areas, I find "artificial tears" can help the eyes a
bit.
I'm sure there's a lot more. It depends on how many are in the party, and
their ages.

Larger bandages and dressings, perhaps.  Some of the smaller first aid
kits I've seen have something along the lines of two 2.5 cm bandages and
a couple of 5 cm x 5 cm dressings.

Additional triangular bandages.  Many kits come with just one.  Chances
are that you won't use any triangular bandages at all, but if you
decided you want to use one, you'll probably need 4 to 6 of them for
immobilisation purposes.

Roll of glad wrap a must!!!!!

I'd incriminate myself if I told you what was in my first aid kit.

Peter Beatie might be reading.