Errors in the charttime or stayid of chartevens

I used the following code to explore whether there are any chartevents that happened after ICU stay:

SELECT 
ce.stay_id,
ce.charttime, 
ce.itemid,
ie.intime,
ie.outtime,
EXTRACT(EPOCH FROM (ce.charttime - ie.outtime))/3600/24 AS days_diff
FROM mimiciv_icu.chartevents AS ce
LEFT JOIN mimiciv_icu.icustays AS ie
ON ce.stay_id = ie.stay_id
WHERE ce.charttime > ie.outtime
ORDER BY days_diff DESC;

To my surprise, there are 407966 records of chartevents that happened after ICU stay. Some of them happened many days or even years after ICU outtime. Compare to the 432997491 records of all chartevents, they are not too many though. How did it happen?

Start with the supplied query and inspect the relationships among mimiciv_icu.chartevents.stay_id, chartevents.charttime, and mimiciv_icu.icustays.outtime. Check representative records with the largest days_diff values and determine why they appear after ICU discharge; done means documenting the cause of these records and whether the data or query needs correction.