It all depends on what the setting is based on the contract roll-over rule and the back-adjustment.
First, the contract rollover can be on either a Thursday or Friday, depending how you set it up.
Then, it can be back adjusted or not.
Me personally, I rollover on the Friday, since the volume ends up being greater by the end of the day on Friday for the new contract. And I don't back-adjust anything. If there is any key level, its usually far away, so it would take a few days to get there, and then the back-adjustment wouldn't make much of a difference I don't think.
On an hourly chart, yes, you would see a gap, but this type of gap is just as likely on a Sunday opening from the Friday close, so its not so unexpected. On a daily chart, you will never notice it as the daily action will more than likely overlap with the close from the previous day of the previous contract. Its possible of course to have a gap on the daily, but I don't recall seeing one in the past few years.