Manhunt reference in Red County

In Fisherman's Lagoon, there is a circle wire holder. On it is a company name and Carcer, which was the city in Manhunt.

Manhunt reference in San Fierro

When you first start the Zero RC toy shop's missions, watch the intermission sequence. Look closely in the background to see action figures of the main character from Manhunt, James Earl Cash.

Manhunt reference in Whetstone

There is a junkyard in the Mt. Chiliad/Shady Creek area that is exactly like the junkyard level in Manhunt. You can also find a Dozer here to drive.