A lot of the limbo plot felt too inconsistent
How was Mal able to convince herself that limbo was the real world and it was logical, possible that she and Dom were able to create buildings just through thoughts? And their children never aged?
How and why was Dom able to, both times, know that limbo world wasn't real, that it was limbo? Why would he want, more than Mal, to leave it?
How would Dom spinning the top and making it keep spinning make Mal think the world was unreal? If she never saw the always-spinning top she wouldn't be affected by it (especially since Dom earlier claimed that projections of someone's subconscious weren't actually parts of the mind) while if she did see it she would more likely realize that it had been tampered with. I get that the top was at least somewhat symbolic but was the flashback some kind of big simplification? This felt like the biggest disappointment as the point of inception was that the manipulated subject would think was his/her own idea (because, albeit through manipulation, they did give the idea to themselves) rather than something someone else planted.