Hackenberg, a former second-round pick by the New York Jets in 2016, signed with the Eagles on Aug. 12. The Jets traded him to Oakland earlier this year for a conditional seventh-round draft pick, and the Raiders waived him three weeks later.
The 23-year-old played in the Eagles' preseason game Thursday against the Jets, completing 7 of 16 passes for 69 yards. In seven drives, he was intercepted twice and sacked twice. He carried the ball five times for 66 yards.
Callahan, 25, a product of Division III program Wesley, now has been waived six times since he signed with Green Bay as an undrafted free agent in 2016. He has been waived six times -- including three times by the Packers.
He fared much better than Hackenberg did on Thursday in the Eagles' 10-9 victory over the Jets. He completed 18 of 26 passes for 164 yards, throwing for one touchdown and one interception.
On Friday, the Eagles also released wide receiver Rashard Davis, tight ends Billy Brown and Gannon Sinclair, and center Jon Toth, according to NJ.com. Davis is a candidate to return to the practice squad.
--Field Level Media