At about 10 minutes in, Stone and Keller were driving in the older (1971 or 1972) Ford Galaxie 500 license 199 CYW. Normally, this season a 1974 Ford Galaxie 500 is used with letters MIB on the license. This was reused footage most likely used to save production costs hoping viewers wouldn't notice.
The 1974 Bell JetRanger II 206B (N59543 s/n 1505) was not a real police helicopter. A banner with the word "Police" was just pasted on and wrinkling could be seen. A real police helicopter would have the blue "SFPD star" on the side. This was a privately owned helicopter and was destroyed/crashed 12/05/2005.