NEW YORK (Real Money) -- What worries people who are smarter than I am? What has them concerned that there are other reasons why we keep going down besides the on-again-off-again, Hamlet-styleFederal Reserve tightening?

I see three real worries that have people buzzing, and I want to point them out, not to scare you but to explain to you how foreign markets interrelate with ours.

First worry: Volkswagen (VLKAY) . Here's the largest maker of autos in the world. Just a gigantic company and it's committed fraud that's far worse than any I can recall by a global company with tentacles in pretty much every nation. The rigging of emissions tests could be regarded as a criminal conspiracy by our Justice Department, which is now bent on going after individuals who did wrong.

While we have a policy in this country, post the wipeout of Arthur Anderson, the big accounting firm destroyed by a Justice Department indictment after Enron, not to crush entire companies for the behavior of a few individuals, the Justice Department's investigation, coupled with the EPA's inquiries, could really do serious damage to this huge company. I would think that every other regulator in every other country will also pounce on Volkswagen.

Any lawyer would tell you that VW has a real bad set of facts on its hands -- even by its own admission -- so the possibility of the company going down the path of BP (BP) - Get Report, or worse, can't be ruled out. A gigantic company that's going to be slaughtered worldwide certainly pops as a sticking point in your stock craw.

Next is Glencore (GLNCY) , a gigantic natural resources company based in Switzerland that is pretty much a black box of commodity exposure. The company's raised money in the equity markets recently, but it has fallen to an all-time low as investors fret about its exposure to slowing commodity prices. Are they right to be so concerned? The issue with all of these is pretty simple: We have no idea, but in this market you have a shoot-first-ask-questions-later attitude about a gigantic company that for all we know has colossal debt exposure that could cause real problems for investors holding its debt.

Finally, there's Petrobras (PBR) - Get Report, the incredibly big Brazilian oil company that has issued a ton of bonds that are in broad retreat. You might be looking at the pathetic stock of what was once among the largest companies in the world -- it now trades at $4, down 44% for the year. But I am looking at the $170 billion in debt the company has and am wondering how it can make the interest payments as the debt is currently configured given the steep decline in oil. This company has some amazing properties, but its balance sheet is way over-levered.

Now, these three sticking points can't bring down our stock market. In fact, one could argue they shouldn't impact us at all. However, I have seen currencies from Southeast Asia and bonds from Russia cause huge damage here when they fell apart in the late 1990s. So who am I to dismiss these concerns now?

No, they are not a reason to run for the hills. Yes, they are proximate causes of what is making many smart people nervous and pull in their bullish horns. I figure knowledge is power and you now have the knowledge these bright managers are discussing around the water cooler and on the trading desks on a daily basis.

Editor's Note: This article was originally published at 10:58 a.m. EDT on Real Money on Sept 22.

At the time of publication, Jim Cramer's charitable trust Action Alerts PLUS held no positions in stocks mentioned.