Visible crew/equipment: During the battle against the dinosaur skeleton, you can see a SFX guy in one shot as the creature whips its head around. He is on the left edge of the screen, standing partially in the frame and visible for nearly a full second.
Visible crew/equipment: Throughout the entire film, you can see lights, cameras, and crew reflected in the Rangers' visors.
Visible crew/equipment: At the end of the film when Fred's dad moves toward him to pull him out of the cherry picker if you look in the bottom left corner of the screen you can see a crew member in the quarry controlling the vehicle. (01:20:15)
Visible crew/equipment: When Tommy is attacking the dinosaur skeleton with a stick you can see some kind of blue equipment or maybe the operator inside the thing as it turns its head towards Tommy. (00:53:20)
Visible crew/equipment: When the rangers are skating past the camera, a camera can be seen reflected on the shorts of Rocky. (00:06:20)
Visible crew/equipment: When Fred is examining his ooze, the camera moves in for a close up and the shadow can be seen moving over Fred's face. (00:41:35)
Visible crew/equipment: Just as the rangers run off from the construction site after losing power, the camera goes in for a close up on the ooze. When it does you can make out the camera shadow in the bottom left of the screen. (00:27:50)
Visible crew/equipment: When the Rangers have landed on the skydive, the camera cuts to everyone leaving the landing zone and a banners covers the screen. When it does, the camera shadow is on the banner. (00:05:00)
Answer: There's never a "point" to including a weakspot, by definition they are a flaw in the design that is either unforeseen or unavoidable. Maybe they could not find a way round it when building the robot, or any solutions simply created other weakspots.