Near the end of the movie, when the zoo apes were freed, they seemed to have joined the revolt to escape to freedom. Were they somehow intelligent by any means? They all left in unison and their behavior didn't seem like that of normal zoo ape that's been kept in captivity. Were they infected by the drug at all?
Also, were these apes the ones that trailed behind on the Golden Gate Bridge?
Below Caesar rolls the canisters to infect the apes in their cages and make them 'intelligent'.
Later the 'intelligent' apes free the apes in the zoo, which then follow them into the city and across the Golden Gate bridge.