Something that the SAB doesn't mark as absurd, but most people reading the Bible in modern times find quite absurd is that fact that immediately after dancing and singing about how great God is and what a wonderful thing it is to be freed from the Egyptians, the Israelites start complaining. "Hey Moses, where's the food?" they ask him. I think it's weird that these guys were about to embark on a journey to a foreign land and didn't think to pack some snacks. As the SAB says later down in the chapter (I'll get to it), the journey from Egypt to Canaan was about ten days. Did they really not have enough to last ten days? Did they really expect Moses to feed all 600,000 of them?
Moses points out to the people that in complaining, they really were complaining to God. The SAB calls this intolerance and injustice, and while I don't agree that these are the issues, I'm not sure which icon(s) would go better here. The point is taken, however, that this sort of claim is used from time to time by religious leaders to manipulate. I would like to stress, however that one might claim manipulation with truth for a good cause is acceptable. For instance, if I were to say to a young person thinking about dropping out of school that people who have had more schooling tend to make bigger incomes, that would be manipulative, but I wouldn't think it morally wrong, intolerant, or unjust at all. In this case, Moses is reminding the people that they've only gotten this far by the grace of God, and they shouldn't take it for granted. Whether you see God in a positive Judeo-Christian light or as an oppressive, capricious supernatural tyrant, this stands to be good advice.
Well, this is where God makes the manna for them. "Manna" is a funny word; the Israelites didn't know what the stuff was, so they called it "What is it?" Of course, modern scholars generally are in agreement with the SAB on the matter, claiming that this mysterious substance was an excretion of certain small insects that fed on tamarisk trees in the region. (An interesting note, but I'm not sure if there is supposed to be an issue with the matter.) The miraculous side of the manna was no so much in existence, then, but rather in its abundance, as there was enough for everyone, and how it kept, namely that it would not last overnight, excepting on Fridays, when it would last for two days. Many scholars believe that the fact that it spoiled was to teach the Israelites to depend on God for daily provision, and the reason it kept on Fridays was obviously so that they would learn about the sabbath.
Ah, the sabbath. That's a hot-button issue. Really, I think the wrong icon is used here, and I'll explain why. Really, there is a matter of interpretive differences that make the true divide between the pro-sabbath and anti-sabbath camps. (Well, there really isn't an "anti-sabbath" camp, just sort of sabbath-neutral.) If you'd like to read about Christians that say, yes, we still ought to keep the sabbath, I'd point you to my friend Newbirth, who has a blog focusing mainly on the topics of low-carb dieting and sabbath-keeping for Christians. For just a lay person in the church, she's done a lot of thought and research into the matter. But as for the Bible...
The SAB gives a page of supposed contradictions concerning the sabbath, and while the items in the "Yes" column are indeed on the mark, I think many of the items in the "No" column are misunderstood. The Isaiah passage is reminiscent of the issue of animal sacrifices I discussed way back in Genesis. Basically God is saying that the Sabbath is something that the Israelites should do to honor God, but they are doing it in a hypocritical display of false self-righteousness, and as such, He despises it. The two passages quoted out of the Gospels, like many others one could find, are not a matter of breaking the keeping of the commandment to observe sabbath, but the breaking of traditional interpretations of the implication of sabbath. It's rather akin to the exchange in Matthew 15, in which Jesus responds to the Pharisees' rebuke about omitting a traditional hand-washing ceremony by pointing out that they don't honor their parents because of man-made traditions. While Jesus did break a few sabbath traditions, I don't believe He ever broke the O.T. sabbath law.
The remaining two verses are admittedly a bit more vague. Paul does sound like he's saying the sabbath is not important. While various people interpret these passages to simply not be saying what you might think they are saying about the sabbath, another possibility that many non-sabbath-keeping Christians point out is that many of the O.T. laws (including the sabbath) were imposed on Jews alone, and not the gentiles. In Acts 15, the early church agrees that there is no need for a gentile convert to Christianity to keep the Mosaic Law, and the sabbath is not specifically mentioned one way or the other.
Coming back full circle to the original issue, the SAB points out that there is something absurd about taking forty years to complete a ten-day journey, and indeed there is. Of course the real reason this happened according to the Bible is that it was due indirectly to the murmuring. The Israelites chose not to go into the Promised Land at the appointed time, so God essentially said, "Okay, then we'll wait forty years and try again when you're really ready." The full explanation is to be found in the book of Numbers.