Other mistake: In the scene where Robin Williams tells Sarah that she needs a 12 to win, she rolls a 3. The next time she rolls, Robin tells her she needs a 7 to win.
Continuity mistake: When Alan is trapped on the floor, and the game is placed over his head, Sarah rolls the dice which fall on the lower left corner. When the angle changes they've moved further to the right.
Continuity mistake: When the Aunt flags down the cop car, the cop has his seat belt on, as the plant starts coming in the car to grab him and the car. He jumps out of the car without ever undoing his seat belt. (01:14:45)
Continuity mistake: When the insect sits on the windowshield of the car Robin Williams says that the insects can't make a hole, they are safe, then the insect makes a hole, the car drives away creating havoc on the road because of extreme bad driving. The car stops, they get out, then there is no hole in the windowshield. (00:40:10)
Factual error: When it's 1969 we see a boy (I'm not sure which one so you'll have to look) riding a Shwinn Sting-Ray Krate Grey. That bike didn't come out until 1971 and they only made them that one year. (00:02:45)
Continuity mistake: Carl's cop car has the licence plate "G2298" which is printed thinly on the licence plate. Then, when the vine wraps around his car, and bends it in two, the licence plate is now "CFJB95", printed very boldly on the plate. The words "POLICE 004" also differ, as does the bumper and the lights. Totally new car, methinks... (01:14:55)
Continuity mistake: When Peter runs out of the attic to the woodshed to get the axe, to the left of the attic door is a large filing cabinet, with nothing in front of it or beside it. Yet later when Peter is swinging the axe at the spiders, and following shots, a green suitcase has appeared in front if it. (01:22:45 - 01:25:00)
Continuity mistake: When Judy is talking with Carl outside the front of their house as Alan examines the police car, Judy's pigtails are alternatively in front of, or behind her shoulders during shots. (00:34:18)
Continuity mistake: When the monkeys are destroying the kitchen the kids open the kitchen door and the monkey on top of the refrigerator knocks the cereal box to the floor. A few seconds later the cereal box is back on top of the refrigerator and the monkey knocks it over only spilling the contents. (00:26:45)
Continuity mistake: At the construction site, Alan claws through the mud, to get to the large metal box. His fingers get covered in mud, yet as he pulls the box out of the mud, and in following shots, the tops of his fingers and his fingernails are very clean. (00:07:00 - 00:07:50)
Continuity mistake: When Sarah, Judy and Peter are in the store, where the riot is going on, they spot the Jumanji Board Game sitting on the till counter. To the right of the till is a very large "Sand and Water Activity Table" box. In one shot the box it facing so you can see the upper part/top of the box. It then cuts, and the box has mysteriously rotated 180°, so that you can now see the lower part/bottom of the box! In the same shots, there is a trolley by the till, with some items and a box in it. Cut back to the trolley and there's now two boxes in it! It then cuts, and the box is back to it's original position, and the box in the trolley disappears! If you look more closely, the entire shelf unit behind the counter is completely different!!! (01:05:55)
Continuity mistake: When Alan is trying to get Jumanji back from the pelican, he grabs a fish from the water, and his sleeve becomes soaking wet. In the next shot his sleeve is bone dry. (00:59:05)
Continuity mistake: In one of the closeups of Alan sitting in the car as it is crashing through the displays inside the Sir Savalot Store, the background, visible through the driver's side window, is of open fields, trees and blue sky. (01:13:00)
Continuity mistake: When Peter rolls the dice prior to letting the monkeys loose, whilst him and Judy are in the attic, he rolls both "1"'s. The sides of the dice which are visible read "3" on one die and "4" on the other. Then when it cuts to a closeup of the boardpiece moving, the "4" now reads a "2", and the dice have also moved position. (00:25:15)
Visible crew/equipment: When grown up Alan is running around shouting "I'm Home!" after just arriving back from the jungle, the camera pans past a grandfather clock, and you can clearly see the legs of a crewmember reflected in the glass panel of the clock, moving in time with the camera. (00:30:50)
Continuity mistake: When the monkeys are causing chaos in the kitchen, a monkey throws three knives at the kids. Two of them stay in the door, but one bounces off and only makes a nick in the wood. Later in the film, when Robin Williams is in the kitchen, and he blocks the door, you can see that the two knives that were stuck in the door are still there, but the nick in the wood has gone. (00:27:10)
Revealing mistake: During the monsoon scene, everyone is on a table trying to climb on the chandelier. Peter has been turned into a monkey, and his face is covered in hair and has the characterists of a monkeys face, yet in shots when they are on the table, like when the crocodile snaps at them on the table, just before Alan lifts Peter onto the chandelier, you can see the plain face of his stunt double, with no monkey features! Robin William's and Bonnie Hunt's doubles are rather obvious in these same shots too. (01:17:20)
Continuity mistake: When Van Pelt comes out of Jumanji, he starts shooting at Alan. Alan then runs through the brown doors, and Van Pelt shoots, misses, and blows a large hole into the door. Yet when they all return to the room, the hole in the door is smaller. (00:53:20 - 00:55:25)
Visible crew/equipment: At the beginning when the bats come out of the fireplace and chase young Sarah out of the house, you can very plainly see the reflection of the cameraman in the door handle after the doors close. (00:14:40)
Visible crew/equipment: In the scene with the big tarantulas, many times you can see the strings attached behind them, especially the one Peter swings the axe at. (01:24:35)
Answer: Since the barb was poisonous, she was dying. This is seen when she begins looking pale and a few seconds later she isn't moving. Finishing the game was the only way to save her life.