Crew or equipment visible

If you look closely at the front grill of Hooker and Romano's car, there's always a square or circular part cut out, revealing the placement of a camera in the car for action shots.

Crew or equipment visible

Launching devices used to flip the cars over during the show's famous car chases are always visible when the car turns over.

Continuity

There are inconsistencies as to how many children Hooker has. In the pilot episode "The Protectors", Hooker is seen only with a young daughter and son. In the first season episode "God Bless The Child", he also has a second daughter who is a teenager. But then throughout the second season, only Hooker's two young children are mentioned. But then from Season Three forward, Hooker only mentions his small daughter.

Miscellaneous

Whenever Hooker is in a hot-pursuit and calls for back-up, there are rarely any units backing them up until the suspect either gets away or is apprehended after a run or small fight.

Continuity

The exterior shots of Hooker and Romano's patrol car almost never match the background processing plates used for the shots of the car interior. For instance, if the exterior shots show them driving through a business district, the interior shots will show them driving through a residential area and vice versa.

Miscellaneous

In numerous instances, cars that have crashed explode violently into flames. Aside from nitrous oxide devices that may be in some cars, there is no reason that a car would simply burst into flames, as petrol is not sufficiently volatile.

Continuity

In a number of instances, a light on a car may be out in one scene, but intact in the next.

Revealing mistakes

In multiple occurrences, one team may be notified that another team is waiting for contact on another Tact channel. The team contacts them - but without physically switching channels. It is necessary to turn the knob on the radio to 'Tact 2' or 'Tact 3' in order to use a different channel other than the main broadcast channel.

Plot holes

Sergeant Hooker started the series with more than 15 years of experience. Since the series spans 5 years, he should have received his fourth 5 year service bar by Series 5, but he doesn't.