The heroine had disabled the security sensors, yet the system's same annoying breathy sultry woman's voice continues to announce Steve's whereabouts.
When Steve tosses the grappling hook to climb the cliff, he is using a blue rope tied to the hook with a neat "compact" knot, but then the next shot of the hook sailing through the air is a reused shot from Steve's training session, with a brown rope and loosely-tied knot; then the shot of the hook catching on the cliff's rocks is with the blue rope and tight knot again.
The torpedo's position (sitting level or tilted upwards) and surrounding scenery (half-buried in surf or sitting on dry beach) changes between shots as Steve lands and climbs out.
The sequence of Steve practicing his tossing of the brown-roped grappling hook is interspersed with bits from the scene of the blue-roped hook being tossed "in real life" on the island; both the brown and blue ropes are seen in this sequence.
The submarine is a modern streamlined design, but the shot of the bow when the torpedo is fired is from a WWII era submarine..
Visible tow-cable for the torpedo as it moves through the water to approach the island.
The image of the island seen through the sub's periscope is the same size/field of view in all the shots, even though the sub is two miles closer in the later shots.
Early in this episode Steve uses a grapple to climb up a rocky hill on the island. This sequence is shot in reverse as evidenced by the waves receding backwards and small rocks falling upwards.
When Austin climbs through "iron" bars that he has bent with his super-strength, his back nudges one of them, and it jiggles, indicating that it is rubber or plastic.
When Balsam was reporting his urgent message in the opening scene, his voice was clearly echoing through the room. However, when Oscar was listening to a recording of the message later, there was no echo in Balsam's voice.
The traveling shot at the beginning that follows the man though the facility from behind eventually turns around when he walks to his right. As the camera pans around, a bright stage light and crew standing next to it can be seen between the machinery in the midground.