As Friday and Gannon are looking for the suspect with the explosives, Friday mentions that they had to hurry yet they are driving slow enough to get passed by the car on the right.
At 9:35 (revealed via narration), Friday and Gannon arrive at the used car dealer in Van Nuys. They are given an address in Sacramento to where the car they are looking for is sold. At 10:15 (revealed again by narration) they arrive at that address. Sacramento is an approximately 6 hour drive from Van Nuys. No way they could have made it there in only 40 minutes.
When the car dealer mentions Sacramento, he says he "mailed the pink slip to Sacramento". He was referring to sending the certificate of title to the DMV in the state capital. The address given to the detectives was in Los Angeles.
When Friday enters Chapman's apartment, he picks up a weapon with his bare hands and then puts it back down. A detective as experienced as Joe Friday should know better than to pick up evidence at a crime scene and contaminate it.