It takes huge ones to file false documents with the SEC, but it does happen and happens more frequently than you would think. Similar to people who file false tax returns with the IRS. They know they can get into big trouble, but ONLY if they're caught. That said, generally speaking if we can't believe SEC filings, what can we believe? Answer: Nothing.
A few words of advice from the SEC:
" ... Caution: By law, the reports that companies file with the SEC must be truthful and complete, presenting the facts investors find important in making decisions to buy, hold, or sell a security. But the SEC cannot guarantee the accuracy of the reports companies file. Some dishonest companies break the law and file false reports. Every year, the SEC brings enforcement actions against companies who've "cooked their books" or failed to provide important information to investors. Read SEC filings — and all other information — with a questioning and critical mind ..."