How did Israel build a wall that big in a week?
And how did the zombies not realise there were people inside earlier?
"I...drink...your...milkshake!"
I don't remember it saying how long Israel had to build the wall. In the book version, I think Israel may have had months of time to prepare but in the movie it's not specified. In the movie, Jurgen Warmbrunn states that the first reports of zombies came from India (the "rakshasha"), followed by reports throughout the Asian peninsula. The soldiers in Camp Humphreys, South Korea encountered a smaller outbreak when the doctor attacked his patients, at which point they E-mailed the U.S., although it was ignored. We don't know how much time went between the Camp Humphreys outbreak and the massive, worldwide outbreak.
However, the soldiers in South Korea state that the doctor's victims turned in roughly 15 minutes, and by the time of the outbreak in Philadelphia and elsewhere, it only takes 10 seconds. We have to assume it took a decent amount of time for the virus to mutate from 15 mins to 10 sec, and who knows how long it took to mutate to 15 mins.
As for the zombies not realizing they were behind the wall earlier, I think the zombies had an idea, but again they're like ants so they were disorganized and scattered. Most of the attention was on the buses bringing in refugees who were protected by the roads surrounded by cages. What tipped off the zombies was when the Israelis, Palestinians, Arabs, etc. started singing their welcome/friendship song. Only one checkpoint was singing though, and the microphone allowed the zombies to figure out where. Once these hoards had one single area to focus on, every zombie in the Middle East suddenly had only one area to attack.
Beforehand, the zombies were breaking against the wall like water which is what the Israelis planned, since the zombies aren't organized and couldn't figure out an attack. However, the singing gave the zombies one area to focus their attack. And by this time, enough of the Middle East had been infected that they had enough numbers to simply pile on each other and make it across. Even before Gerry Lane says "It's too loud," you can see IDF and Palestinian soldiers beginning to get nervous and start sending soldiers to break it up; unfortunately they were too late.
Can't be too careful with all those weirdos running around.
"Even before Gerry Lane says "It's too loud," you can see IDF and Palestinian soldiers beginning to get nervous and start sending soldiers to break it up; unfortunately they were too late."
Would shooting the singers have helped or would that have just created more concentrated noise