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If you want to show reviews for products you sell I recommend gathering and using your own reviews. If you don't have the volume for that and still want to show reviews, maybe consider an iFrame. It depends on the service and how their feeds/scripts work. For example, if the script is in a folder that is blocked in the robots.txt file, Google will not be able to access it and will not be able to render that content.

I respectfully disagree. While it may not be considered duplicate content, it also can be. In fact, if you look at Google's own suggestions on https://support.google.com/webmasters/answer/66359?hl=en: Minimize boilerplate repetition: For instance, instead of including lengthy copyright text on the bottom of every page, include a very brief summary and then link to a page with more details. In addition, you can use the Parameter Handling tool to specify how you would like Google to treat URL parameters. -- So sure, Google says you shouldn't worry about it but if 10% of your pages content is repeated on each page, that could or could not be an issue.. why take that chance? If your actual products don't have much unique content to describe it, the boilerplate content reduces the relevance of the page. You suggestion of a "pop-up/model window on a single page linked from the product pages" is the best way to minimize boilerplate content and avoid any chance of worse rankings.

Thanks Everett! yes there's definitely seo benefit from having the title in the URL, and I think it's pretty significant - from what I have seen previously when we made a massive url changes for one of the websites I worked on - went from /{id}/ to {id}-{product-title}. Also there is a study shows that display url in search results is still a prominent element to influencing searchers' clicks. This is from 2012 but I think the same still applies today. http://research.microsoft.com/pubs/155941/domainbias.pdf so I'd prefer to have the titles included. It is completely possible to make the very original static, and that would be my preferred option - but we need to assess whether the changes were made because they were "mildly" or "totally" incorrect in the first place, and also at the same time need to convince others - who feel keeping the original urls (when the product titles change) would worsen ux. 301 redirects would be totally mental - so this would not be an option. Also adding canonical tag to the "non-original" urls method - potentially ok in the short term. I think using static (hardcoded) urls would be the only long-term solution.