The steady exodus of top executives from Erol's Inc. continues. The latest official to leave the Springfield-based video rental firm is Robert J. Morick, vice president for merchandising and marketing, who has joined an Arizona-based drugstore chain in a similar position.

Morick, who was in charge of buying videotapes and coordinating advertising and promotion for the 200-store Erol's chain, said his departure was the result of a challenging job offer rather than because of any problems at Erol's. Morick, a veteran drug store marketing executive who joined Erol's in April 1989, said his new job allowed him to return to the industry he knows best.

"If it was anything but this sort of opportunity, I wouldn't have left the company," said Morick, who earlier this month became vice president and part-owner of Glendale, Ariz.-based RDS Revco, which operates 147 drugstores in the Southwest.

In recent months Erol's has lost several key executives to arch rival Blockbuster Entertainment Corp. and this summer announced the resignation of company president Carl Bellini for "personal reasons."

Industry analysts have suggested that Bellini and other executives have left the chain because of friction with chairman and founder Erol Oneran.

An Erol's spokeswoman said Morick's duties would be handled by Vice Chairman Peggy Chittal until a successor is named.