Unbound Controls
Text boxes bound to Date fields are not a problem, but if the control is unbound (nothing in its Control Source property), how can Access know what data type you intend? If you are in the USA, it will probably guess correctly. If you use another date format, there's a high probability that your date will be interpreted wrongly.
In general, the Format property of the control has to do with how Access displays data and does not control data entry. However, if you set the Format property to "Short Date" or similar, Access is unable format an invalid entry, so only valid dates are accepted. And since Access now knows the data type, the erroneous interpretations of the date also cease.
As simple as it sounds, setting the Format property is enough to coerce Access into recognizing the data type for unbound controls.