Regarded as a particularly hard tackler on defense and a powerful runner of the football, Castiglia was elected 1936 team captain by his teammates at the end of the 1935 season.

[4] In the third game of the 1940 season against Temple University, Castiglia popped a 16-yard run up the middle for a touchdown, helping the Hoyas continue their undefeated record that dated back to 1937.

[5] During his 1940 senior season, Castiglia missed time due to a hip injury,[6] but nevertheless gained the notice of some pro football talent scouts.

[12] Castiglia never played for the Steelers, who assigned his rights to the Philadelphia Eagles ahead of training camp for the 1941 NFL season.

[11] Castiglia was apparently released by the Tigers, but was subsequently invited by the Philadelphia Athletics to their 1942 spring training in Florida as an unsigned bullpen catcher.

[18] Among Castiglia's duties while stationed in Missouri was coaching the football team of the 30th Training Group of the Army Air Forces.

Castiglia remained in uniform as a US Army Air Forces officer through 1945, although he did manage to use furlough time to make his way from Greensboro to join the Philadelphia Eagles in their November 25, 1945, game against the Washington Redskins.

[24] He was apparently released from the team shortly thereafter and on April 22 he signed a contract to play football for the Philadelphia Eagles for 1946.

[23] On August 4, 1947, head coach Cecil Isbell announced that Jim Castiglia had signed a contract with the Baltimore Colts of the new All-America Football Conference (AAFC).

Although he only played two games for the Colts, Castiglia holds the honor of scoring the first touchdown in the history of the Baltimore franchise.

For the September 7 opener at the original Baltimore Municipal Stadium, the Colts kicked off to their opponents, the Brooklyn Dodgers, on a muddy field in a heavy rain.