Visible crew/equipment: When Jo shuts her door after setting up Dorothy III during the final monster tornado scene, the heads of three crew members are reflected in the silver window frame.
Continuity mistake: When we see the dog Mose in the movie he looks very young (2-3 years old). But in the scene when Bill and Joe's storm chasers crew watches Jonas's van gets picked up by the F5 tornado, the dog Mose has aged 5-6 years (when dogs age the fur around the face turns white).
Visible crew/equipment: There's a shot late in the movie at Helen Hunt's Aunt's house - the camera shows all of her home made "wind chimes" blowing in the wind. As the camera pans in and shows a little man sawing or axing something, you see a human hand appear near the bottom of the screen as the camera leaves the scene.
Continuity mistake: During the first tornado, Beltzer says the twister is about three miles away. You later see Bill turn the truck off the road directly onto that dirt path, not ten yards away. The tornado then arrives and sucks Jo's truck into the air. After the tornado, Melissa is driving along and says, "Oh my God" as the tornado disappears, back to about three miles away.
Visible crew/equipment: When the twister is heading for the drive-in movie theater, as Bill is running towards the garage, you can easily see the shadow of the Steadicam operator and a grip guy on the ground about 2 feet away from Bill's shadow.
Factual error: When Jo and Bill drive through the house pictures are still on the wall, a chair is still upright and the towels are still hanging perfectly on the rack in the bathroom. Pretty cool considering the house had just been tumbling through a field.
Factual error: In the last scenes when Bill and Jo are in the shed with the water pipes, the shed is torn apart by wind as well as flying debris at hundreds of miles per hour. I have watched the scene numerous times and there is not so much as a scratch on their faces. Even if they lived, they would have been battered and bloody from debris. Regardless if tornadoes do weird things, the debris ripped the shed apart, which is stronger than a human body.
Visible crew/equipment: When Bill Paxton and Helen Hunt are driving up to Aunt Meg's house after the tornado has hit, you see a shot of the ruined home as they drive up. If you look carefully, you can see wires hanging coming out from the top of the house to keep it from collapsing until the filmmakers were ready.
Factual error: After the 3rd twister knocks down Dorothy, spilling the micro balls on the pavement, Jo yells at Bill to stop the truck so she can gather them up, Bill grabs at her to stop, calling her obsessed over something that happened when she was a child. The camera then zooms in on the truck CB radio airing their conversation live. Which would be impossible considering that type of old school handheld receiver requires a human finger depressed over the button to talk.
Other mistake: When Paxton and Hunt are in the shed at the end attaching themselves to the water pipe with the straps, there is an above shot looking down at them. If you look outside the window you can see corn husks barely moving on the ground despite there being an F-5 right outside.
Visible crew/equipment: When the red Dodge truck stops spinning after the "sisters" tornado has gone, as the camera moves up the truck to focus on the occupants, you can see part of the camera rigging reflected on the truck wing/fender.
Continuity mistake: In the garage scene, an air hose comes on and Preacher grabs it. When he is hit by a hub cap and lets go of the hose, the air switches off.
Visible crew/equipment: After leaving Wakita, Bill and Jo are driving through a cornfield. The cornfield merges into the main road and their truck almost runs into Jonas' fleet. As the truck enters the road, you can see a crew member poking his head up from the corn across the road. Watch above the driver's side mirror.
Continuity mistake: When we see Melissa at Aunt Meg's house, she is in the same 3-piece white suit she's been wearing since the start of the movie and it is still spotless - even after Bill, dirty, muddy and wet from the first tornado, hugs her.
Revealing mistake: When they are at the drive-in movie place, Melissa comes out of her room when she sees the wind blowing through the curtains. When she steps out, other windows in the motel are open and the curtains are absolutely still while the curtains in her room continue to blow.
Other mistake: During the garage scene, we see a large neon sign get ripped off of its mounting pole and thrown into the garage. It seems obvious that the sign is no longer connected to any sort of electricity source, however, the sign stays lit as it is ripped off its pole, into the next shot when it crashes into the garage, and then it continues to flicker a bit as it lays on the ground.
Other mistake: The first time we see the NSSL; the woman's name there is Chris. Later in the movie, when we see the NSSL again, her name is Bryce. Turn the captions on so you can tell.
Continuity mistake: About halfway through the film, when they all take shelter in the garage near the drive in movie, when the 'Drive In Movie' sign goes crashing through the garage wall you can clearly see a large metal chain pulling it through.
Other mistake: In the scene in the garage pit, one of the characters is hit in the forehead by a flying hubcap. He is cut clear across his forehead, but there is only a small trickle of blood oozing from the wound. I've seen many scalp lacerations and even the most minor ones will bleed like a stuck pig, where's all of that blood?
Factual error: We all know that when any tornado is on the ground and/or near moving towards us, things get blown around, like trees, grass, and other things. There are two things that I found that didn't look right. It's in the scene when the F-5 tornado is chasing Bill and Joe to the Barn. First the grass and cornfield are moving but not the trees. And second, when the tornado blows away the brown picket fence we see most of the pickets shoot upwards, which is impossible because they are nailed to horizontal boards. It would either take a far stronger wind than they're currently in to rip the pickets straight up, or the pickets were made out of far cheaper wood than they appear to be.
Answer: Based on his scenes, he seems to be a photographer for the team. He was taking pictures of Jo, showing how Dorothy worked, and was setting up a camera when Bill and Jo were going after the F5 at the end.