Visible crew/equipment: During the Quidditch match Harry's broomstick tries to shake him off, due to the spell. After Hermione tells Ron, "Leave it to me," in Harry's last close-up before he flips over, the seat that is attached to the broomstick, to make it more comfortable for Dan Radcliffe to sit on, is entirely visible. Glimpses of other seats can be had during the match as well. (01:20:50)
Visible crew/equipment: At the Quidditch match, after Hermione sets Snape's cloak on fire and someone shouts, "Fire! You're on fire!" there is a close-up of Harry with his hands gripping the Nimbus 2000. In this shot, the wire rods which are attached/taped to the broomstick, near Harry's fingers, that lead under both of his red sleeves, are entirely visible. (01:21:35)
Visible crew/equipment: Being chased by the flying keys, as Harry zips by on the broomstick he tosses the key, Hermione catches it and runs to the door. In the next shot, a close-up, as she tries to unlock the door, an electrical cable hangs down beside the column, that was not in the previous shots. There is also an electrical cable coming out from under the back of Hermione's sweater that is blatantly visible as well. (01:59:55)
Visible crew/equipment: After Quirrell announces there's a troll in the dungeon, Dumbledore shouts, "Silence!" and soon continues, "Teachers will follow me to the dungeons." In the following shot of McGonagall, the wires that the candles hang from are plainly visible. (01:09:00)
Visible crew/equipment: Petunia has her hands on Dudley's eyes as they walk towards all of his birthday gifts. When she removes her hands from Dudley's eyes, in this shot and in the next, the long black microphone wire as well as its tape, which obviously peeled free, are blatantly visible and are sticking out at the neckline of her v-neck top under the pearl necklace. It's gone in the following shots. (Do not confuse the blue apron strings for the mic wire.) (00:05:00)
Visible crew/equipment: After falling from the Devil's Snare, Harry tells Ron, "Lucky Hermione pays attention in Herbology." Then as Ron starts to walk toward Harry, there is a crew member's arm and hand gripping the back of Ron's shirt at the bottom. (Visible on DVD fullscreen.) (01:57:45)
Visible crew/equipment: In the scene where Hermione, Ron and Harry are returning to Gryffindor's tower room after being in the third floor room for the first time, you are able to see the feet of one of the crew. It happens just as they are passing through the picture hole, where Harry turns a couple of times to check that the "door" is closing. And it is in fact, because someone is walking behind it and pushing it shut, since the picture hangs several inches off the floor. (01:02:55)
Visible crew/equipment: Hermione opens the door to Fluffy's room when she says, "Alohomora!" so she, Harry and Ron could hide from Filch and Mrs. Norris. As Ron closes the door the top of the third floor corridor set is visible at the top of the screen. As an aside, when Ron repeats, "Alohomora!" look at Hermione's face. (01:02:00)
Visible crew/equipment: After the Queen attacks the Knight's horse during the chess game, Ron goes flying back and falls. In the shot as he hits the ground, the black protective gear that he wears is visible when his grey T-shirt rolls up and the button on his left cuff is open, yet closed in the next close-up. (02:05:15)
Visible crew/equipment: Dumbledore tells Harry that he will move the Mirror of Erised and not to go looking for it. In the following shot Harry walks outside in the snow with Hedwig on his arm. In the close-up of Hedwig, the jess (strap) around his left leg is visibly tethered to Harry's sleeve. The inside of Harry's sleeve also has a strap that secures the sleeve around Harry's wrist. Hedwig is obviously not tethered in the next shot. (01:36:45)
Visible crew/equipment: During the Quidditch match as the players ride their broomsticks, visible in quite a few shots are the two wires that are attached to the broom handle, between their legs, that extend down with a clamped loop that goes around their feet. In some shots the wires between their legs are edited, but the wire loops around their feet are perfectly visible, like in the following example. When the Slytherin score hits 10 onscreen, in the next shot, as Flint shouts, "Take that side," the wire is completely visible at his right foot under his cloak. Two examples where the entire wires are visible are, when Flint grabs the club and says, "Gimme that!" the wires are blatantly visible and he then proceeds to slam the Bludger into Wood, who falls. Next close-up of one of the twins, the wires are visible before Flint starts to leap over him. (Don't confuse the cloak's long front ties for the wire). (01:19:00)
Visible crew/equipment: Petunia and Dudley enter the house when they return from the zoo, followed by Vernon and Harry. The crew's equipment is plainly visible on the ground beyond the doorway. Also, the pavement at the threshold extends far beyond the doorway and just before Vernon walks into the house, Vernon is visibly coming from the side of the doorway. In the earlier exterior shot when they stand by the car before they leave, as Vernon says, "I'm warning you now boy...," not only is the ground at the doorway completely different, there is a garden surrounded by white bricks beside the door, making it impossible for Vernon to have been standing there. (Visible on DVD fullscreen.) (00:05:40 - 00:08:05)
Visible crew/equipment: Harry, Ron and Hermione run to Hagrid's hut to tell him that they know about the Stone and they knock on the door. As Hagrid opens the door in the first shot looking out, Harry stands behind his tape mark and Hermione and Ron visibly stand behind their shared black tape MARK on the step. (01:38:35)
Visible crew/equipment: When the Queen attacks Ron's horse during the chess game, in the shot from behind Ron as he falls, the black straps attached to the horse's left rear leg, used to aid the stunt, are completely visible. (02:05:15)
Visible crew/equipment: After escaping Devil's Snare, Harry, Ron and Hermione enter the Key room. When Ron says, "You're the youngest seeker in a century." In the next shot of Harry as he grips the broomstick, the wire that it hangs from is clearly visible at its bristles. (01:59:15)
Visible crew/equipment: At the end of term feast, Dumbledore stands and says, "Another year gone." In the next shot of the Gryffindor table, part of the camera equipment is actually visible at the lower right corner of the screen. (01:17:55)
Visible crew/equipment: In the Key room after Hermione asks, "What's this all about?" Ron takes his wand out and starts for the door. In the wide shot facing the door as he and Hermione pass to Harry's left the BAR attached to the underside of the broomstick bristles is visible. It is not visible in other shots. (01:58:30)
Visible crew/equipment: In Hagrid's hut, Harry, Ron and Hermione gather round the table as Hagrid places the dragon egg in the center. As the egg starts to hatch the shell flies everywhere and between Hermione and Hagrid camera equipment is visible at the lower left corner of the screen. This area is clear prior to this one shot obviously. (01:40:10)
Visible crew/equipment: Harry, Ron and Hermione are in Hagrid's hut and the egg inside the cauldron in the fireplace starts rattling. In the shot looking up at Hagrid from behind the cauldron, at the top left of the screen in front of the fireplace, as Hagrid retrieves the egg a piece of equipment comes down then quickly goes back up and at the top in the center there is a small black film square that is not part of the fireplace. (01:39:35)
Visible crew/equipment: As the troll begins to lift Harry with his huge club in the girls' lavatory, in the overhead shot as Harry hangs on to the edge of the 'real' club, at the bottom left of the screen the crew's blue equipment is perfectly visible. (Visible on DVD fullscreen.) (01:10:50)
Answer: Petunia or Vernon would have ran to a zoo employee and told them what happened. The employee would then open the door to the snake exhibit letting Dudley out.