Upon an appeal taken by the defendant, the appellate court may, without exception having been taken in the trial court, review any question of law involved in any ruling, order, instruction, or thing whatsoever said or done at the trial or prior to or after judgment, which thing was said or done after objection made in and considered by the lower court, and which affected the substantial rights of the defendant. The appellate court may also review any instruction given, refused or modified, even though no objection was made thereto in the lower court, if the substantial rights of the defendant were affected thereby.