The antonyms for the phrase "arriving in time" would be "coming late" or "missing the deadline". These are the polar opposites of the phrase which imply that the individual or object in question is not able to reach its destination or fulfill its task within the allotted time frame. Additionally, words such as "delayed", "overdue", "belated" and "tardy" can also be considered as antonyms for the phrase. Such antonyms are significant, especially in professional or academic settings where punctuality and timeliness are highly valued traits. They bring to light the negative consequences that can arise if one fails to arrive on time or complete tasks within the given time limit.