Malloy and Reed are asked to respond to the 211 at the grocery store "Code 3" i.e. urgent, lights and siren. Malloy is seen reaching for the "lights and siren" switch before they are asked to respond Code 3. NOTE: An experienced police officer would know the radio transmission (before it is complete) will be a Code 3 . . . so, this is not really a goof.
When Reed escorts the manager out of the grocery store, it is supposed to be empty with the exception of Malloy. A man wearing a red shirt can be seen moving in the background inside the store immediately behind Malloy in a dark alcove.