The way ministries and agencies handle public funds is a top issue of concern that will be debated in Parliament when it sits on Monday.
Their lapses, described in the latest annual report of the Auditor- General's Office (AGO), have prompted nine Members of Parliament to file questions for debate.
They include Mr Desmond Choo (Tampines GRC), who said: "As guardians of public money, every statutory board, every ministry, should take this very seriously.''
He and Mr Low Thia Khiang (Aljunied GRC) highlighted the overpayment of volunteer police officers that went undetected from 2008 to last year. The sum involved was $2.63 million.
Mr Choo asked: "Why, over seven years, did we not uncover this? Now, how are we going to recover that amount? It is unfair to ask the volunteers to return their pay, too."
Another hot-button issue concerns the hairline cracks found on 26 MRT trains that were subsequently sent back to the manufacturer in China to be repaired.
Non-Constituency MP Daniel Goh is asking whether the defects, which the Land Transport Authority (LTA) said were not "safety-critical", pose zero safety risks to commuters in layman's terms.
"I am a commuter. I would be concerned about cracks and whether they pose any safety risks.
"If there are nagging questions or phrases that are not absolutely clear, it would be important for the authorities to clarify them to fully assure the public," said Dr Goh, one of four Workers' Party MPs who have filed questions on the episode for Transport Minister Khaw Boon Wan.
Mr Sitoh Yih Pin (Potong Pasir), who chairs the Government Parliamentary Committee for Transport, wants to know why people were not told of the cracks when they were discovered three years ago.
In all, 108 questions on a range of issues were filed for debate, but queries on the AGO report top the list.
Ms Lee Bee Wah (Nee Soon GRC) wants to know why the LTA and the Immigration and Checkpoints Authority could not coordinate their operations, as a result of which nearly $14 million in toll charges was not collected at the Causeway checkpoints.
"The ministries work in silos. The guy who checks passports thinks that whether people pay the toll or not is none of his business. More can be done to get them to cooperate more closely, " she told The Straits Times.
Other concerns of MPs include Singapore's fight against terrorism and the controversy over risque orientation games at the National University of Singapore.
Associate Professor Fatimah Lateef (Marine Parade GRC) also asked for an update on security preparations to counter terrorism here. "Singapore has many soft targets. An attack can happen any time, anywhere," she said.
Six Bills are up for debate, including the Administration of Justice (Protection) Bill that seeks to clarify laws on contempt of court.
Three Nominated MPs have called for changes to some clauses in the Bill. This follows a petition signed by 249 Singaporeans who are concerned that the new law may restrict legitimate discussion of issues that are of public interest.
A Bill involving changes to the Consumer Protection (Fair Trading) Act will also be introduced.