Hi Andrestone,
Recently I had a set of threads discussing about similar issues. What you should know:
1- QC uses an ImmediateFill when you place a market order. This means that if you are testing with high resolution data, your tests may not ber very realistic. So you may want to add an artificial delay to your orders.
2- When you place a Limit (or Stop Limit) order, it might get partially filled or not filled at all until a lot later (or never). So you need to track your tickets and probably cancel them if needed.
3- If you place an order with 1 million share, the framework will fill it for you. In real life that is not how it might work. So, it's good to be aware of the volume and quote data in real life.
If you are dealing with lower resolutions, these may not cause any problem at all.