Organisers were more focused and confident than when I last visited and construction work appeared to have come on in leaps and bound. This optimism was confirmed by the International Olympic Committee’s (IOC) Coordination Commission as they crowed about how all Rio’s promises were coming true and, as I wrote last week, I feel a broadly successful Games is in order this time next year.

But Coordination Commission chair Nawal El Moutawakel mixed her praise with a warning that much more work lies ahead over the next 12 months, with "a million details" still needing to be addressed. With sleep proving impossible and all films worth watching having been watched on my flight home, I began an impromptu brainstorming session as to some of the remaining challenges…

• Water pollution levels are the most talked about concern but, much as organisers are trying to downplay fears, it is a real problem. Legacy commitments to reducing levels by 80 per cent are not going to be met - although the new IOC line is you cannot say they have failed because it is "very hard to calculate a percentage" - so its impact on athletes is now the focus. Fifteen members of the United States rowing team became ill after the recent test event, but it is claimed this has nothing to do with pollution because a coach who had not been on the water was also ill and a rower who capsized was not. Yet, despite officials acting as if it is, this is not conclusive proof and it appears strange no viral as well as bacterial testing will be conducted. The ongoing sailing test event on Guanabara Bay is another major test, and if there are more illnesses, pressure will grow for changes to be made to the courses.

• As many people have said, the pollution focus does reveal good progress with venue construction but the final completion of venues will still be tricky. For instance, while most of the Lagoa Rodrigo de Freitas rowing venue is nearly done, problems remain with the installation of two floating grandstands on the other side of the course, something that, if not resolved, will detract from both the atmosphere and capacity. Finishing the Broadcasting Centre in time for the relevant infrastructure to be installed will be another challenge, and there must be similar teething issues with many other venues, something you would expect at this stage but a challenge nonetheless.

• Perhaps more hazardous is the completion of infrastructural projects vital to the success of the Games. National Federation officials at the equestrian venue warned that the road between Deodoro and the Athletes' Village in Barra de Tijuca must be improved, while there have been concerns that the Subway extension linking Ipanema to Barra will not be ready in time. Rio 2016 President Carlos Nuzman has insisted he is not worried about the June 2016 deadline not being met, but if it was not ready there would be real problems due to the ill-equipped nature of the sole road linking the two hubs. At rush-hour times this is already a huge bottleneck, particularly in a narrow tunnelled section, and there is not an obvious alternative route. Making sure the international airport can cope with increased demand is also crucial.

• Efficiency. This is a slightly vaguer point, but Rio have to make sure volunteers and everyone else is fully trained to perform their tasks with perfection, paying attention to every detail. This was all done so well at recent Games I have attended in London, Sochi, Nanjing, Baku and Toronto and doubts do remain as to whether Brazil can match them. No one is expecting impeccable organisation in Rio de Janeiro, but it will only take a few bad experiences for spectators, or a few instances of media transport or Wi-Fi not working, and criticism will begin to mount. Involvement from those who have organised major Games before will hopefully make this easier.

• Safety and security of all those attending the Games is one of the biggest lingering fears and, like with other problems, a couple of muggings before the Opening Ceremony when the world’s media is in place with few other stories to write, and there could be an international outcry. As during last summer’s World Cup, a heavy police presence will provide reassurance, albeit at the expense of a slight atmosphere of intimidation. The danger will be if tourists stray off the beaten track, with the Deodoro Hub particularly close to some of the most dangerous parts of the city.

• Not being associated with the Government. Let’s face it, Brazil is in a mess right now with a mire of corruption scandals accompanying the abject poverty. Support for Dilma Rousseff’s Government has plummeted to the extent some believe either resignation or an impeachment is possible, and a latest wave of mass demonstrations were held against her across the country yesterday. It appears the Games is too important to be lost amid this fallout but it is vital it is viewed by the population as a ray of sunlight amidst the gloom rather than another Government project. I think this is generally being avoided so far but I wonder how glad organisers really are about the "closer role" being paid by President Rousseff, something that in itself suggests she sees the Games as a project worth associating with.

• Benefiting poorer as well as the wealthier inhabitants was another key appeal of Rio’s bid, regenerating deprived areas such as Deodoro with new housing, facilities and transport infrastructure. Yet in a country with an increasingly clear rich-poor gap, there is a feeling that the Games will only benefit one section of the population. The Athletes’ Village is set to be converted only into high-end apartments. Construction giant Carlos Carvalho, who is set to pocket $1 billion (£650 million/€900 million) from Olympic-related development work, even quipped how the main Games hub at Barra will become an elite "new Rio" with the poor confined to other parts of the city. I was surprised by the expensive nature of Games-related memorabilia, with the smallest mascot in the official store costing BRL R$99 (£18/$28/€25), while Rio Mayor Eduardo Paes is yet to fulfil a pledge to buy one million tickets for poor schoolchildren. It is unrealistic for the Games to change too much, but more action must be taken to match the rhetoric.

• Public interest and support at the moment is still far from universal, with Brazilian ticket sales so far good rather than great. This is partly due to how the Games is still a year away, but there is also a feeling money would be better spent elsewhere. It does bear remembering how many in Britain felt the same ahead of London 2012, and it was the Torch Relay and then the Opening Ceremony which did most to change public opinion, so the big challenge will come next year.

There are other issues as well, some of which they will have successfully hidden from the media spotlight. Ticketing scandals are probably not something which could detract from the overall success of the Games, but after the problems with Match Hospitality at the World Cup, they are a concern. Following the surfeit of allegations in recent weeks, there must also be fears of a major doping scandal during the Games. While it is not anything to do with the organisers, the Pan American Games in Toronto were slightly overshadowed by the large number of cases and to my generation, Seoul 1988 still conjures up images of Ben Johnson more than anything else.

It is crucial now that organisers don't get complacent following good progress and these creases must be ironed out over the next few months.