There should be a variety of methods to induce critical thinking. Discussions are the first, and most used, method for critical thinking, but it is surprisingly limited. Just like there are different ways people learn, there are different ways people best engage and provide feedback. You can write a well-developed response to a discussion post that uses minimal critical thinking if you know how to write well. You can also write a poorly-developed response to a post even though maximum critical thinking effort was made if you are not a good writer. 

Online active learning can open up engagement factors to real-world applications. Staying in the classroom limits tactile examples to only what is portable.

Limitations for active learning need to be revisited by accrediting agencies. Many schools would probably be open to adjusted hours or alternative educational assessments, but they are hampered by accreditation requirements. Also, educators already spend their own money to facilitate their classes, so it can be hard to utilize some engagement activities when the resources are not being provided.

Active learning requires the instructor to do more than just read a lecture. It also requires more active participation from students.

Not having the immediate interaction of in-person class can be difficult for students if they are having issues. Staying engaged and providing quick responses can help. It is also important to monitor discussions to make sure everyone is participating appropriately.

Asynchronous discussions are able to be more informative and deliberate. Synchronous discussions are more suited to one-on-one or enhanced with a video. I had a professor once set up a video chat at the beginning of the semester to answer any questions students had for real-time feedback. A few things he did to get around some of the downsides to synchronous chats were to have students send email questions ahead of time that he could address on the chat, he recorded the chat and made it available to everyone, and he scheduled a second chat on a different day of… >>>

Having a short biography at the course beginning can be useful for students to put a person behind the name. 

Knowing how to navigate the course and troubleshoot issues are critical. Being a live resource for students is imperative.