EXERCISE 13–8 Shifts: mood and voice, questions and quotations
Example:

The master chef asked her apprentice to add more salt to the soup and don’t forget to taste it before dinner service.

The master chef asked her apprentice to add more salt to the soup and reminded her to taste it before dinner service.

The incorrect sentence shifts from the indicative mood (the master chef asked), which is used for statements of fact, to the imperative mood (don’t forget), which is used for commands.